CHEMICAL BONDS

CHEMICAL BONDS
Chemical bonds are formed when the electrons in an atom interact with the electrons in another atom. This allows for the formation of more complex molecules.

3 Types of Chemical bonds

*Covalent
These strong bonds form when two atoms share electrons.
Sometimes the electrons in an atom get shared. It's much like when you were a kid and got to sleep over at a friends house. Your friends parents were in charge of you both for one night and the next night you would sleep over at your house and your own parents would be in charge. This sharing of responsibility is functionally similar to the way covalent bonding works.

Normally this sharing is an equal proposition. Sometimes it's not equal (but that gets us into hydrogen bonding discussed below.)

*Ionic
Atoms gain or lose electron (opposites attract)
Ions have positive or negative charges. In dating situations, you may know that sometimes opposites attract. In Chemistry, opposites ALWAYS attract. This forms an ionic bond between two atoms.

*Hydrogen
Weakest bond between atoms
Occurs in molecules that have covalent bonds. Sometimes the electrons are not equally shared; one atom tends to have an electron more often than the other atom. In this situation one atom of the molecule becomes partly negative and the other then becomes partly positive.
Now we have positive and negative things becoming attracted to each other. (remember ionic bonds?) This is especially common between water molecules.

Shapes of Simple Molecules

Understanding the shapes of molecules is an important first step in being able to discuss and predict chemical properties. We shall discuss here some "simple" molecules. This topic, however, has important applications in understanding the behavior of much larger molecules. Much of biochemistry is now being discussed based on how macromolecules are shaped, and how different molecules "fit" together.
It is observed that the SF2 molecule is bent, the F-S-F bond angle being 98°. The BeCl2 molecule, however, is linear. Why are these two AX2 type molecules so different?

SF2

BeCl2

To understand any molecule, one must first complete a Lewis dot structure. It is then possible to predict the molecular shape using TWO BASIC PRINCIPLES:
1. The shapes of molecules are determined by the repulsion between electron pairs in the outer shell of the central atom. Both bond pairs (electron pairs shared by two atoms) and lone pairs (those located on a central atom but not shared) must be considered.
2. Lone pairs repel more than bond pairs.
The application of these principles is best seen by referring to specific examples. We shall start looking only at molecules with single bonds (for simplicity).

A. Central atoms with less than octet configurations: The BeCl2 molecule has a Lewis dot structure as shown. The central Be atom has two bond pairs in its outer shell. Repulsion between these two pairs (first principle above) causes the molecule to be linear (see above). If the molecule were bent in any direction, the two bond pairs would be brought closer together, increasing the repulsion.
The molecule BF3 has a dot symbol as:

BF3 :

Here the B atom has three bond pairs in its outer shell. Minimizing the repulsion causes this molecule to have a trigonal planar shape, with the F atoms forming an equilateral triangle about the B atom. The F-B-F bond angles are all 120°, and all the atoms are in the same plane.

B. Central atoms with octet (noble gas) configurations:
The CH4 molecule has a dot structure as shown. The shape of this molecule, however, is not planar, as is suggested by the way we draw this dot structure.

CH4 :

Carbon has 4 bond pairs. The four H atoms are arranged about the C atom in a tetrahedral shape . This shape minimizes the repulsion between the bond pairs. The 109.5° angle is the same for all H-C-H bond angles and is called the tetrahedral angle.

There are many molecules that have four bond pairs and this regular tetrahedral shape; CCl4, SiF4, and SnCl4 are just a few examples.

The molecule NH3 has a dot symbol much like that for BF3 (see above). Now, however, there is a lone pair in the outer shell of the central N atom.

NH3 :

In NH3 the N has 3 bond pairs and 1 lone pair, (4 total pairs). The shape is called trigonal pyramidal (approximately tetrahedral minus one atom).

WHACHACALLIT: A shape name is based on what is experimentally observed - the location of atomic nuclei. In NH3 the N, with 4 e pairs, will have a tetrahedral electron pair orientation. (The total number of e pairs determines the electron pair orientation.) The lone pair occupies one corner of the tetrahedron. It is difficult to "see" lone pairs experimentally. Looking only at the atoms, we see a short, rather distorted tetrahedron. This is called a pyramid. The pyramids of Egypt have square bases. The NH3 pyramid has a triangular base. Hence the shape is called trigonal pyramidal.

LONE PAIR DISTORTIONS: Due to the greater repelling character of lone pairs, (second principle above) the H atoms in NH3 are bent closer together than the normal tetrahedral angle of 109.5°. In NH3 the observed angle is 107.3°. Other molecules with this one-lone, three-bond-pair configuration (:NCl3 and :PCl3) have this same trigonal pyramidal shape, slightly different bond angles, but all less than 109.5°.

The H2O molecule has this dot structure:

H2O:



The O in H2O has 2 bond pairs and 2 lone pairs (again, 4 total pairs). The electron pair orientation around O is tetrahedral. Two corners of the tetrahedron are "missing" because they are occupied by lone pairs, not atoms. The shape is called bent. The H-O-H bond angle is 104.4°. This angle is less than that in NH3, due in part to the greater repulsions felt with two lone pairs

Other molecules with 2 bond plus 2 lone pairs include OF2, H2S, and SF2. Bond angles vary, but all are significantly less than 109.5°.

C. Central atoms with expanded octet
configurations:
A number of molecules have more electrons in the outer shell than in a noble gas configuration. This involves use of one or more d orbital (so as to not violate the Pauli Exclusion Principle). We will not worry, for now, about the types or shapes of the orbitals involved in the bonding, but will only consider electron pair repulsions.

The PCl5 molecule has 5 bond pairs in the outer shell of P. This molecule has a symmetrical trigonal bipyramidal shape.

PCl5 :

Note that the Cl atoms occupy two types of positions. The two Cl atoms which are on a straight line which passes through the P nucleus are said to occupy axial positions. The other three Cl are in equatorial positions.
NOTE:The axial Cl to P bond distance is slightly longer than the equatorial Cl to P bond distance.

Valence-Shell Electron-Pair Repulsion Theory (VSEPR)

There is no direct relationship between the formula of a compound and the shape of its molecules. The shapes of these molecules can be predicted from their Lewis structures, however, with a model developed about 30 years ago, known as the valence-shell electron-pair repulsion (VSEPR) theory.
The VSEPR theory assumes that each atom in a molecule will achieve a geometry that minimizes the repulsion between electrons in the valence shell of that atom. The five compounds shown in the figure below can be used to demonstrate how the VSEPR theory can be applied to simple molecules.


There are only two places in the valence shell of the central atom in BeF2 where electrons can be found. Repulsion between these pairs of electrons can be minimized by arranging them so that they point in opposite directions. Thus, the VSEPR theory predicts that BeF2 should be a linear molecule, with a 180o angle between the two Be-F bonds.
There are three places on the central atom in boron trifluoride (BF3) where valence electrons can be found. Repulsion between these electrons can be minimized by arranging them toward the corners of an equilateral triangle. The VSEPR theory therefore predicts a trigonal planar geometry for the BF3 molecule, with a F-B-F bond angle of 120o.
BeF2 and BF3 are both two-dimensional molecules, in which the atoms lie in the same plane. If we place the same restriction on methane (CH4), we would get a square-planar geometry in which the H-C-H bond angle is 90o. If we let this system expand into three dimensions, however, we end up with a tetrahedral molecule in which the H-C-H bond angle is 109o28'.
Repulsion between the five pairs of valence electrons on the phosphorus atom in PF5 can be minimized by distributing these electrons toward the corners of a trigonal bipyramid. Three of the positions in a trigonal bipyramid are labeled equatorial because they lie along the equator of the molecule. The other two are axial because they lie along an axis perpendicular to the equatorial plane. The angle between the three equatorial positions is 120o, while the angle between an axial and an equatorial position is 90o.
There are six places on the central atom in SF6 where valence electrons can be found. The repulsion between these electrons can be minimized by distributing them toward the corners of an octahedron. The term octahedron literally means "eight sides," but it is the six corners, or vertices, that interest us. To imagine the geometry of an SF6 molecule, locate fluorine atoms on opposite sides of the sulfur atom along the X, Y, and Z axes of an XYZ coordinate system.



Polarity of molecules

A compound is comprised of one or more chemical bonds between atoms. The polarity of each bond within the compound determines the overall polarity of the compound: how polar or non-polar it is. A polar molecule usually contains polar bonds - bonds which have unequal sharing of electrons between the two atoms involved in bonding. A non-polar compound usually contains non-polar bonds - bonds which have identical or similar sharing of electrons.Besides bond polarity, the other factor that decides if a molecule is polar is the molecule's symmetry. Even if a compound contains only polar bonds, it may be non-polar overall as the direction of the polarities cancel each other out, giving the molecule a net polarity of zero. This occurs in boron trifluoride, which contains three identical polar bonds all canceling each other out due to their symmetrical arrangement. Trigonal planar, tetrahedral and linear bonding arrangements often lead to symmetrical, non-polar molecules which contain polar bonds. On the other hand, even if a compound contains only non-polar bonds, it may be polar overall if it is a non-symmetric shape; for example, all the bonds in ozone are non-polar (between atoms of the same element), but the ozone molecule is nevertheless polar, because of its bent shape and the resulting asymmetry in electron distribution.



Intermolecular Forces

Water is the only substance we routinely encounter as a solid, a liquid, and a gas. At low temperatures, it is a solid in which the individual molecules are locked into a rigid structure. As we raise the temperature, the average kinetic energy of the molecules increases, which increases the rate at which these molecules move.
There are three ways in which a water molecule move: (1) vibration, (2) rotation, and (3) translation. Water molecules vibrate when H--O bonds are stretched or bent. Rotation involves the motion of a molecule around its center of gravity. Translation literally means to change from one place to another. It therefore describes the motion of molecules through space.

To understand the effect of this motion, we need to differentiate between intramolecular and intermolecular bonds. The covalent bonds between the hydrogen and oxygen atoms in a water molecule are called intramolecular bonds. (The prefix intra- comes from the Latin stem meaning "within or inside." Thus, intramural sports match teams from the same institution.) The bonds between the neighboring water molecules in ice are called intermolecular bonds, from the Latin stem meaning "between." (This far more common prefix is used in words such as interface, intercollegiate, and international.)
The intramolecular bonds that hold the atoms in H2O molecules together are almost 25 times as strong as the intermolecular bonds between water molecules. (It takes 464 kJ/mol to break the H--O bonds within a water molecule and only 19 kJ/mol to break the bonds between water molecules.)
All three modes of motion disrupt the bonds between water molecules. As the system becomes warmer, the thermal energy of the water molecules eventually becomes too large to allow these molecules to be locked into the rigid structure of ice. At this point, the solid melts to form a liquid in which intermolecular bonds are constantly broken and reformed as the molecules move through the liquid. Eventually, the thermal energy of the water molecules becomes so large that they move too rapidly to form intermolecular bonds and the liquid boils to form a gas in which each particle moves more or less randomly through space.
The difference between solids and liquids, or liquids and gases, is therefore based on a competition between the strength of intermolecular bonds and the thermal energy of the system. At a given temperature, substances that contain strong intermolecular bonds are more likely to be solids. For a given intermolecular bond strength, the higher the temperature, the more likely the substance will be a gas.
The kinetic theory assumes that there is no force of attraction between the particles in a gas. If this assumption were correct, gases would never condense to form liquids and solids at low temperatures. In 1873 the Dutch physicist Johannes van der Waals derived an equation that not only included the force of attraction between gas particles but also corrected for the fact that the volume of these particles becomes a significant fraction of the total volume of the gas at high pressures.
The van der Waals equation is used today to give a better fit to the experimental data of real gases than can be obtained with the ideal gas equation. But that wasn't van der Waals's goal. He was trying to develop a model that would explain the behavior of liquids by including terms that reflected the size of the atoms or molecules in the liquid and the strength of the bonds between these atoms or molecules. The weak intermolecular bonds in liquids and solids are therefore often called van der Waals forces. These forces can be divided into three categories: (1) dipole-dipole, (2) dipole-induced dipole, and (3) induced dipole-induced dipole.

Dipole-Dipole Forces
Many molecules contain bonds that fall between the extremes of ionic and covalent bonds. The difference between the electronegativities of the atoms in these molecules is large enough that the electrons aren't shared equally, and yet small enough that the electrons aren't drawn exclusively to one of the atoms to form positive and negative ions. The bonds in these molecules are said to be polar, because they have positive and negative ends, or poles, and the molecules are often said to have a dipole moment.
HCl molecules, for example, have a dipole moment because the hydrogen atom has a slight positive charge and the chlorine atom has a slight negative charge. Because of the force of attraction between oppositely charged particles, there is a small dipole-dipole force of attraction between adjacent HCl molecules.



The dipole-dipole interaction in HCl is relatively weak; only 3.3 kJ/mol. (The covalent bonds between the hydrogen and chlorine atoms in HCl are 130 times as strong.) The force of attraction between HCl molecules is so small that hydrogen chloride boils at -85.0oC.

Dipole-Induced Dipole Forces
What would happen if we mixed HCl with argon, which has no dipole moment? The electrons on an argon atom are distributed homogeneously around the nucleus of the atom. But these electrons are in constant motion. When an argon atom comes close to a polar HCl molecule, the electrons can shift to one side of the nucleus to produce a very small dipole moment that lasts for only an instant.

By distorting the distribution of electrons around the argon atom, the polar HCl molecule induces a small dipole moment on this atom, which creates a weak dipole-induced dipole force of attraction between the HCl molecule and the Ar atom. This force is very weak, with a bond energy of about 1 kJ/mol.

Induced Dipole-Induced Dipole Forces
Neither dipole-dipole nor dipole-induced forces can explain the fact that helium becomes a liquid at temperatures below 4.2 K. By itself, a helium atom is perfectly symmetrical. But movement of the electrons around the nuclei of a pair of neighboring helium atoms can become synchronized so that each atom simultaneously obtains an induced dipole moment.

These fluctuations in electron density occur constantly, creating an induced dipole-induced dipole force of attraction between pairs of atoms. As might be expected, this force is relatively weak in helium -- only 0.076 kJ/mol. But atoms or molecules become more polarizable as they become larger because there are more electrons to be polarized. It has been argued that the primary force of attraction between molecules in solid I2 and in frozen CCl4 is induced dipole-induced dipole attraction.

ACTIVITY 1

ACTIVITY 1

Comparing Ionic and Covalent Compounds

I.Purpose:
- to compare the physical properties of ionic and covalent compounds
- to determine whether an unknown substance is ionic or covalent

II.Materials:
burner sodium chloride (A)
conductivity apparatus potassium iodide (B)
scoopula potassium chloride (C)
deflagrating spoons - 2 sugar (D)
watchglass benzoic acid (E)
beakers (7) camphor (F)
unknown solid

III.SAFETY PRECAUTIONS:
Safety glasses must be worn. Caution when heating compounds to determine melting point. The molten state may sputter. IT WILL BURN. Follow teacher's directions about conductivity apparatus.

IV.Procedure:
Before beginning the experiment, create a chart for your observations on a new sheet of paper. Determine suitable headings for your columns based on the rest of the method section of this paper. One column should be a prediction of the type of substance - either covalent or ionic.
(1) Try to detect if any of the substances have an odour. Wave your hand over the substance toward your face. Record your observations.
(2) Ignite a burner. Place a small sample of substance (A) into one deflagrating spoon and a small sample of substance (D) into the other. Record the one that melts first as low, and
the other's melting point as high. You do not need to melt the one with the higher melting point. Thoroughly clean the spoons before continuing.
(3) Repeat step (2) for substances (B) and (E).
(4) Repeat step (2) for substances (C) and (F).
(5) Repeat step (2) for your unknown.
(6) Determine whether each substance seems hard or soft. Do this by first rubbing a small sample of each between your fingers. Then try to crush a few crystals of each. Place each compound in the watchglass one at a time, and use a scoopula to try to crush them.
(7) Make a solution of each compound in separate beakers.
(8) Use the conductivity apparatus to test the solutions of each of the seven substances.

V.Observations:
Create a chart for your observations before beginning the lab activity from the instructions. Predict whether the substances are ionic or covalent (see Pre-lab question 1).

VI.Questions/Discussion:
Pre-lab questions:
(1) Based on what you've learned about electronegativity differences and bond types, predict which group of elements (A-C) or (D-F) are ionic and which are covalent.
(2) Outline the procedure in a series of pictures.
Post-lab questions:
(1) Compare the physical properties of ionic and covalent substances.
(2) What is the number of your unknown? Is it an ionic or covalent substance?
(3) Intermolecular forces exist between molecules or ions. Based on this lab, which do you think are stronger i) intermolecular forces between covalent molecules or ii) intermolecular forces between ions?
(4) Covalent compounds can be found as single molecules, but ionic substances can't be found as single ion pairs. What evidence do you have for this fact?
(5) Which type of substance conducted electricity when dissolved in water? What is different between ionic and covalent substances that causes this?

VII. Generalization:

ACTIVITY 2

ACTIVITY 2

The Wave Bottle

I. Objective:

To create a wave bottle by using liquids of different densities and polarities.

II. Discussion: Mineral oil will not mix with water (because it is nonpolar and water is a polar solvent). It is also less dense than water, and thus will float on top of the water. Food coloring is not soluble in mineral oil, but is readily soluble in water (in fact, it is purchased as a water solution). Careful observation when the food coloring is added to a bottle containing water and mineral oil allows us to "see" the results of the collisions of molecules. The water in the wave bottle consists of many water molecules. The molecules of food coloring spread erratically throughout the water, changing direction when they collide with the water molecules, until they are thoroughly mixed with them. When you perform the experiment, notice also that when falling through the mineral oil, the cohesive forces of the drop of food coloring pull it into a sphere, minimizing its surface area. Vegetable oil can also be used in place of mineral oil, but it is colored and may become rancid. Vegetable oil is a mixture of triacylglycerols obtained from vegetable sources. While not extremely reactive under normal conditions, it will react with oxygen over a period of time to produce some discoloration. . Mineral oil is a mixture of liquid hydrocarbons obtained from petroleum, and is considerably more inert than vegetable oil.

III. Materials: A clear, colorless bottle with a cap, enough mineral oil to half fill the bottle, water, food coloring.

IV. Procedure:
Fill the bottle ½ full of mineral oil. The bottle must be clean and contain no soap residue.
Fill the bottle the rest of the way with water. Observe which liquid ends up on top and which on the bottom.
Observe carefully as you add several drops of food coloring. Start out with only a few drops. If you want a darker solution, you can always add more later.
Put the cap on the bottle and tighten firmly.
Turn the bottle on its side, rock it back and forth, and observe.

V. Questions:
1.Which liquid is less dense and floated on top?
2.Describe what happened when the food coloring was added to the mineral oil.

3.Describe what happened when the food coloring entered the water layer.
4.What other liquids could be used to prepare a wave bottle?

VI. Generalization:

ATOMS IN THE PERIODIC TABLE

Atoms in the Periodic Table
The idea of the atom as being the irreducible constituent of matter is central to our current understanding of nature. According to Feynman, if there was one sentence that he could communicate to a future civilization that has lost all scientific knowledge, it would be the atomic hypothesis, namely that `` all things are made of atoms - little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another''. This single sentence contains the key to regaining almost all of the current theories of science.



Chemical Symbols
At one time chemists used various symbols, similar to shorthand, for the atoms of the different elements. These symbols were very cumbersome and were replaced by abbreviations of the names of the elements. Each element has been assigned a specific one or two letter symbol based on the first letter of its chemical name. Because there are several elements with the same first letter, it is often necessary to add the second letter to the symbol. In some cases the symbol comes from an abbreviation for the old latin name of the element. For example, Fe stands for iron (ferrum) and Cu for copper (cuprum). The first letter of the chemical symbol is always capitalized. If the symbol has two letters, the second letter is always lowercase.

Some of the abbreviations for the names of elements make sense--H for hydrogen, C for carbon, He for helium. But some of them seem completely random. What's the deal?
Some elements have been given symbols based on their names in Latin, which was once commonly used by scientists as an international language.
Scientists have adopted certain conventions regarding the chemical symbols for various elements. The symbol is the short form or abbreviated name of the element. Each element has a chemical symbol that is unique to it. An atom of an element is denoted by this symbol. For example, the symbol for Oxygen is O.
Many elements have their symbol derived from either the first letter [e.g., N for Nitrogen] or the first two letters [e.g., Ne for Neon] of their names. A few elements have symbols derived from their Latin names [e.g., the symbol for Lead is Pb, short for Plumbum].

The Periodic Table

The periodic table of the chemical elements is a tabular method of displaying the chemical elements, first devised in 1869 by the Russian chemist Dimitri Mendeleev. Mendeleev intended the table to illustrate recurring ("periodic") trends in the properties of the elements. The layout of the table has been refined and extended over time, as many new elements have been discovered since Mendeleev's time, and new theoretical models have been developed to explain chemical behavior. Various layouts are possible to emphasize different aspects of behavior; the most common forms, however, are still quite similar to Mendeleev's original design.
The periodic table is now ubiquitous within the academic discipline of chemistry, providing an extremely useful framework to classify, systematize and compare all the many different forms of chemical behavior. The table has also found wide application in physics, biology, engineering, and industry. The current standard table contains 117 confirmed elements as of October 16, 2006 (while element 118 has been synthesized, element 117 has not).

Notes
Lanthanides are also known as "rare earth elements", a deprecated term. Regarding group membership of these elements, see here.
Alkali metals, alkaline earth metals, transition metals, actinides, lanthanides, and poor metals are all collectively known as "metals".
Halogens and noble gases are also non-metals.

Families of Elements

Elements are divided into two catagories: metals and non-metals.
Metals and non-metals have different physical and chemical properties.
Physical Properties of Metals
– shininess (luster)
– conduct heat and electricity very well
–high density
–ductile – can be drawn into thin wire
–mallable – can be hammered into thin sheets
Chemical Properties of Metals
–not as easy to see
–chemical properties depend on the way electrons are arranged in the atom.
–an atom of a metal can have 1-4 electrons in its outer energy level.
–these valence electrons are weakly held: metals lose electrons easily.
–most metals are reactive with water or elements in the atmosphere
–this results in corrosion of metal
Corrosion – wearing away of metal as metallic element is changed into a compound.
rust 4Fe + 3O2 >> 2Fe2O3
copper oxide (green) 2Cu + O2 >> 2CuO
Tarnishing of Silver 2Ag + O2 >> Ag2O

Alloys – a mixture of a metal and another element. Alloys have the properties of metals. The other element can be a metal or a non-metal.
most famous alloy: steel Fe + C >> Steel
Steel + Cr + Ni >> Stainless steel
Steel is stronger than iron.
Other alloys: Cu + Sn >> Bronze
Cu + Zn >> Brass
Dental fillings: Hg + Ag
Solder Pb + Sn
14 carat gold Au + Cu + Ag

Physical Properties of Non-Metals
Non-metals have no luster, dull in appearance
Non-metals don’t conduct heat or electricity well
Non-metals are brittle and break easily–they are not mallable or ductile
Non metals are not as easy to recognize as metals. Not all are solids–some are liquids (Br) or gasses (O, Cl, N).
Chemical Properties of Non-Metals
Non-metals like to gain electrons, not lose them.
Most non-metals have 5-8 electrons in their outer energy level.
Atoms with 5, 6 or 7 valence electrons tend to gain 3, 2, or 1 electrons to fill up outer energy level.
Metalloids
some elements display properties of metals and non-metals – metalloids.
All metalloids are solids, but not very shiny.
White or gray in color
conduct heat and electricity fairly well.
Active Metals – Group IA (1) and Group IIA (2) of the periodic table.
Group IA – the Alkali Metals ns1
Li, Na, K, Rb, Cs, Fr
–These metals are soft, not very dense – can be cut with a knife.
–most reactive metals – never found in nature as pure elements
–must be stored in oil to prevent keep from reacting with the air — do not touch!
–reacting with water – produces H2, heat – can explode
–this reaction produces alkali base NaOH (lye)
Alkali metals have 1 electron in their outer energy level.
This electron is easily lost
When an electron is lost, what is the charge on the atom? +
Charged atoms are called ions. Alkali metals form postive ions.
Products made from alkali metals: salt, baking soda, soap.
Very important in our bodies, especially in blood.
Na used in vapor lamps, nuclear reactors — produced by electrolysis of salt.

Group IIA – Alkaline Earth Metals ns2
Be, Mg, Ca, Sr, Ba, Ra
not as reactive as group IA
higher melting and boiling points
harder and denser than IA
never found alone in nature
Mg – found in medicines, flashbulbs, flares
Ca – limestone – needed for bones of vertebrates, seashells
CaO (quicklime) is a very important industrial chemical made from limestone:
CaCO3(s)CaO(s) + CO2(g)
Quicklime is reacted with water to produce calcium hydroxide (slaked lime)
CaO(s) + H2O(l) ® Ca(OH)2(aq) + heat
Plaster and mortar are products of slaked lime. Acid soils are neutralized using this material.



Group IIA – the Boron Family ns2np1
Boron is a metalloid – hard and brittle, never found by itself in nature. Does not form +3 ion readily because of its small size (electrons are tightly held)
Na2B4O7 (Borax) is the most common borate mineral (found in S California)
Used in making glass, cleansers (borax), water softeners, insecticides.
Al is the most common metal (metalloid). The third most common element in the earth’s crust. Found in the mineral corundum — impure aluminum oxide.
Rubies are corundum crystals with a few Cr ions substituting for Al.
Al is light, strong, does not react with air.
Good conductor or electricity
What is it used for? cans, wiring, airplane and car parts, cookware, alloys.
Used to be rare, and expensive in pure form — the trick was to dissolve corundum — Charles Hall discovered cryolite (Na3AlF6) does the job
Aluminum foil – is Al mallable?
Gallium, Indium, and Thallium are rare.
Gallium is used in semiconductors. It has a wide temperature range (mp 30° C, bp 1980° C) which makes it good for use in thermometers.

The Carbon Family – Group IVA ns2np2
includes C, Si, Ge, Sn, Pb.
Some are metals, some are non-metals, others are metalloids.
Carbon
- has millions of known compounds – forms the basis of life
- Compounds containing carbon are called organic compounds.
- Compounds that don’t contain carbon – inorganic compounds
- Carbon has 3 allotropes — graphite, diamond, buckminsterfullerene
Silicon
- second most common element in the earth’s crust
- Sand is made of Si and O – used to make glass.
Ge – used to make transistors
Sn – is corrosion-resistant.
Tin cans are made of steel, with a thin layer of Sn on the inside.
Bronze is an alloy of Sn and Cu.
Solder is an alloy of Sn and Pb.
SnF2 is used in toothpastes
Pb – the densest of the carbon family.
Used to be used in paints and gasoline. Not anymore – is considered unsafe, especially for children.
Isolated from galena, PbS

The Nitrogen Family – Group VA ns2np3
Contains N, P, As, Sb, Bi
Nitrogen
- is not very reactive – makes up most of the atmosphere
- found in fertilizers, explosives, drugs, dyes, cleaners (ammonia)
very important element in our bodies – proteins
- bacteria contain enzymes that "fix" nitrogen, breaking triple bonds and converting it into usuable forms.
isolated by distillation from liquified air, or heating over red-hot coke
ammonia manufacturing is most important use of nitrogen:
ammonia used as a fertilizer (ammonium sulfate), starting material for nitric acid (explosives)

Phosphorus
is much more reactive than N.
Very important in the body — ATP, DNA, bones
Pure P exists in red or white forms. White allotrope is very reactive.
Arsenic is a poison – used in insecticides
Bismuth and Antimony are used in printing presses.
The Oxygen family – Group VIA ns2np4
Oxygen
- is most abundant element in crust, 2nd most abundant in atmosphere.
- O is essential for most forms of life. Respiration requires O2.
- Oxygen is very reactive. At high temperatures, combines rapidly with other elements – combustion (burning of wood)
like nitrogen, prepared by liquifying air and distillation.
Used for manufactuing steel, medicine
Ozone is an allotrope of oxygen
When substances combine with oxygen, the process is called oxidation, and the product is an oxide.
Oxides of metals are commonly solids, oxides of non-metals can be any phase and usually react with water to form acids.
Sulfur
- pale yellow solid, very important industrially
is used in gunpowder, insecticides, matches, rubber, paints, plastics dyes
sulfuric acid manufacturing — most common industrial chemical
several allotropes, including S8 (monoclinic), rhombic sulfur, amorphous sulfur.
Commonly forms sulfides when heated with metals
Selenium — semiconductor used in photoelectric cells and copy machines
Tellurium — very rare

The Halogens – Group VIIA ns2np5
Fl, Cl, Br, I, At – most active non-metals, never found by themselves
each has 7 valence electrons–gaining one more completes their energy shell.
halogens have low MP and BP
can exist as diatomic elements (two atoms of the same element)
F – found in teflon, refrigerants, toothpaste, used to separate isotopes of uranium.
Cl– found in bleach, used as disinfectant, salt, PVC plastic
Br, I –disinfectant, dyes I is essential for life.
Hydrogen
most abundant element in the universe
free H is rare, compounds are common (1% of crust)
water is most common compound
present in carbohydrates, fats, proteins
fossil fuels
composed of 3 isotopes
not a metal, not a good conductor of heat or electricity
has some properties of group VIIA as well as group 1A — unique!
Used to manufacture ammonia, hydrogenation of fats
Can be prepared in several ways:

Noble Gases – Group VIIIA ns2np6
Noble gases do not react with any elements. They are inert gases.
Their outer energy levels are filled up
Ar makes up 1% of atmosphere. Mendeleev didn’t know about these gases
He is found in the sun and other stars, used in balloons, deep sea diving
Xe makes a few compounds
Ne is used to make neon lights
Ra is used to treat cancer
Transition Metals (n-1)d ns
Transition metals have properties that are different from the other eight families.
These are the famous metals: Ag, Cu, Ni, Au, Hg, Pt Zn
Transition metals are excellent conductors of heat and electricity
much less active than other metals
high melting points, are pretty hard
most combine with O2 to form oxides
each element can lose different numbers of electrons.
Oxidation number – the number of electrons that an element gains, loses or shares with another element when it chemically combines.]

Rare-Earth Elements – very similar to each other
lanthanoid series – soft metals, good conductors, oxidation state is 3+
used to make glass
actinoid series – radioactive elements; most are synthetic, 3+

Properties of Elements in the periodic table

The properties of the elements exhibit trends. These trends can be predicted using the periodic table and can be explained and understood by analyzing the electron configurations of the elements. Elements tend to gain or lose valence electrons to achieve stable octet formation. Stable octets are seen in the inert gases, or noble gases, of Group VII of the periodic table. In addition to this activity, there are two other important trends. First, electrons are added one at a time moving from left to right across a period. As this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction, so the electrons become closer to the nucleus and more tightly bound to it. Second, moving down a column in the periodic table, the outermost electrons become less tightly bound to the nucleus.

This happens because the number of filled principal energy levels (which shield the outermost electrons from attraction to the nucleus) increases downward within each group. These trends explain the periodicity observed in the elemental properties of atomic radius, ionization energy, electron affinity, and electronegativity.

Atomic Radius
The atomic radius of an element is half of the distance between the centers of two atoms of that element that are just touching each other. Generally, the atomic radius decreases across a period from left to right and increases down a given group. The atoms with the largest atomic radii are located in Group I and at the bottom of groups.
Moving from left to right across a period, electrons are added one at a time to the outer energy shell. Electrons within a shell cannot shield each other from the attraction to protons. Since the number of protons is also increasing, the effective nuclear charge increases across a period. This causes the atomic radius to decrease.
Moving down a group in the periodic table, the number of electrons and filled electron shells increases, but the number of valence electrons remains the same. The outermost electrons in a group are exposed to the same effective nuclear charge, but electrons are found farther from the nucleus as the number of filled energy shells increases. Therefore, the atomic radii increase.
Ionization Energy
The ionization energy, or ionization potential, is the energy required to completely remove an electron from a gaseous atom or ion. The closer and more tightly bound an electron is to the nucleus, the more difficult it will be to remove, and the higher its ionization energy will be. The first ionization energy is the energy required to remove one electron from the parent atom. The second ionization energy is the energy required to remove a second valence electron from the univalent ion to form the divalent ion, and so on. Successive ionization energies increase. The second ionization energy is always greater than the first ionization energy. Ionization energies increase moving from left to right across a period (decreasing atomic radius). Ionization energy decreases moving down a group (increasing atomic radius). Group I elements have low ionization energies because the loss of an electron forms a stable octet.

Electron Affinity
Electron affinity reflects the ability of an atom to accept an electron. It is the energy change that occurs when an electron is added to a gaseous atom. Atoms with stronger effective nuclear charge have greater electron affinity. Some generalizations can be made about the electron affinities of certain groups in the periodic table. The Group IIA elements, the alkaline earths, have low electron affinity values. These elements are relatively stable because they have filled s subshells. Group VIIA elements, the halogens, have high electron affinities because the addition of an electron to an atom results in a completely filled shell. Group VIII elements, noble gases, have electron affinities near zero, since each atom possesses a stable octet and will not accept an electron readily. Elements of other groups have low electron affinities.

Electronegativity
Electronegativity is a measure of the attraction of an atom for the electrons in a chemical bond. The higher the electronegativity of an atom, the greater its attraction for bonding electrons. Electronegativity is related to ionization energy. Electrons with low ionization energies have low electronegativities because their nuclei do not exert a strong attractive force on electrons. Elements with high ionization energies have high electronegativities due to the strong pull exerted on electrons by the nucleus. In a group, the electronegativity decreases as atomic number increases, as a result of increased distance between the valence electron and nucleus (greater atomic radius). An example of an electropositive (i.e., low electronegativity) element is cesium; an example of a highly electronegative element is fluorine.

Summary of Periodic Table Trends
Moving Left --> Right
Atomic Radius Decreases
Ionization Energy Increases
Electronegativity Increases
Moving Top --> Bottom
Atomic Radius Increases
Ionization Energy Decreases
Electronegativity Decreases

Important Metals in the Body

More than 30 elements have a key function in helping plants and animals live and be healthy.
Everything around us is composed of chemical elements. Elements are the basic building blocks of our lives. Elements combine with one another in different proportions to form everything from the air that we breathe, to the wood that we use to build our homes, to our own bodies.
Our bodies use different chemical elements for different functions. For instance, our bodies use calcium to build strong bones and fluorine makes our teeth healthier. As our bodies consume these elements through daily functioning, we have to replace them in order to stay healthy and strong. The greatest source of these elements is through the food we eat. Because some of us do not always eat the right foods, we sometimes have to take dietary supplements, such as vitamins, to assure that we maintain the proper chemical balance in our bodies.
Some of the major elements that our bodies use to function properly are described in the following paragraphs. Some surprising minor elements are also described.
Aluminum (Al)
Until recently, aluminum was thought to be useless to life processes. It is now thought to be involved in the action of a small number of enzymes. For a technical explanation: "it may be involved in the action of enzymes such a succinic dehydrogenase and d-aminolevulinate dehydrase (involved in porphyrin synthesis)." I have no idea what that means.
Even if this element is necessary for some life function, the amount necessary is greatly exceeded by our incidental intake through our drinking water, food, deodorants and some antacids. Aluminum is relatively benign, and it is used in food additives and indigestion pills. It has been linked to Alzheimer's disease and the body has a hard time ridding itself of excess aluminum. Aluminum is somewhat more toxic to plants.

Arsenic (As)
Despite Arsenic’s reputation as a highly toxic substance, this element may actually be necessary for good health. Studies of animals such as chickens, rats, goats and pigs show that it is necessary for proper growth, development and reproduction. In these studies, the main symptom of not getting enough arsenic was retarded growth and development. It is suspected, but not known, that arsenic is necessary . It is thought to be necessary for the functioning of the nervous system and for people to grow properly. Since arsenic is present in our food and water, all humans have some arsenic in their bodies and a deficiency of this element in humans has apparently never been observed. An arsenic trioxide has been approved by the Food and Drug Administration to treat a rare and deadly form of leukemia called acute promyelocytic leukemia, or APL.

Boron (B) - a micronutrient
At first, boron may seem like an unimportant, uncommon and boring element. But boron is actually required by the body in very small amounts, and is necessary for good health. Though it is commonly known that calcium builds strong bones, boron is also important. Bones are not just the dead, white, stone-like things we see on skeletons. In our bodies bones are constantly breaking down and being rebuilt. They also have a constant blood supply and are very much "alive". Without small amounts of boron, bones would slowly break down and become brittle.
This element is also necessary to allow the brain to function properly. In fact, boron can increase mental alertness. According to a series of studies recently conducted by the US Department of Agriculture, low boron intakes by humans caused decreased brain activity. The studies showed that people on low boron diets also had lower brain performance on attention and short-term memory tests.
Our bodies also need boron in very small amounts to allow calcium, magnesium and phosphorus to function properly. So in a sense, boron is also necessary for many other body functions and we could not survive without it.

Bromine (Br)
This is another element that is probably not necessary for good health and no deficiency of this element has ever been documented. Bromine is suspected to be an essential trace element in red algae and possibly humans. No specific role for this element in human health has been identified. Bromine is found in the mollusk pigment "royal purple", but it’s purpose in that pigment is not known.

Cadmium (Cd)
Mixed opinions on cadmium. While it is definitely believed to not be essential for plant and animal life processes, some believe cadmium is a trace element with some necessary role in life processes. Although its need and use are not currently understood. It is thought to be involved with the metabolism Its status as an essential trace element remains unclear.

Calcium (Ca) - a macronutrient
Calcium is an extremely important element in the human body. It is one of the most abundant elements in our bodies and accounts for 2 to 3 pounds of our total body weight. Most of us know that calcium is important in building and maintaining strong bones and teeth, but it is also important for many other things. It helps control things like muscle growth and the electrical impulses in your brain. This vital element is also necessary to maintain proper blood pressure and make blood clot when you get cut. Calcium also enables other molecules to digest food and make energy for the body. Increasing calcium intake in our diet is believed to lower high blood pressure and prevent heart disease. It is also used to treat arthritis.
When we don’t get enough calcium, many things happen in our bodies. It is possible to get leg cramps, muscle spasms, our bones may become brittle and even we may even have an increased risk of getting colon cancer. Also, when we don’t get enough calcium in our diets, our bodies will actually use the calcium that we have stored in our bones. This makes the bones thinner and more brittle. In growing children and teenagers the bones may not develop fully and the person can enter adulthood with brittle bones. Further calcium deficiency can lead to serious problems.
Therefore, it is extremely important to get enough calcium in your diet. Unfortunately, that is not always easy to do. Most Americans don’t get enough from their diets. But eating a good balanced diet, including drinking milk on a daily basis, should get you enough calcium.

Carbon (C) - a macronutrient
The element carbon is perhaps the single most important element to life. Virtually every part of our bodies is made with large amounts of this element. The carbon atom is ideal to build big biological molecules. The carbon atom can be thought of as a basic building block. These building blocks can be attached to each other to form long chains, or they can be attached to other elements.
This can be difficult to imagine at first, but it may help to think about building with Legos. You can think of carbon as a bunch of red legos attached together to form one long chain of legos. Now, you can imagine sticking yellow, blue and green legos across the tops of the red (carbon) legos. These other colors represent other elements like oxygen, nitrogen or hydrogen. As you stick more and more of these yellow, blue and green legos to the red chain, it would start to look like a skeleton of legos with a "spine" of red legos and "bones" of yellow, blue and green legos. This is a lot like the way that big molecules are made in the body. Without carbon, these big molecules could not be built.
Now, virtually every part of your body is made up of these big molecules that are based around chains of carbon atoms. This is the reason we are known as "carbon based life forms". Without carbon, our bodies would just be a big pile of loose atoms with no way to be built into a person.

Chlorine (Cl) - a micronutrient

Anyone who has ever swallowed a mouthful of water at a swimming pool would probably tell you that chlorine is one of the most unpleasant things they have ever swallowed and they wouldn’t mind if they never ingest chlorine ever again. This element, however, is actually essential for humans to live - we would die without it. Chlorine is found throughout the body; in the blood, in the fluid inside cells and in the fluid between cells.
Along with sodium and potassium, chlorine carries an electrical charge when dissolved in body fluids. This is why these elements are termed "electrolytes". The electrical charge that these elements carry is what allows nerve cells to work. Chlorine also works with potassium and sodium to regulate the amount of fluids in the body and to regulate pH in the body. This vital element also helps muscles flex and relax normally.
Stomach acid is a compound of hydrogen and chlorine (hydrochloric acid, or HCl). Logically, chlorine is extremely important in allowing us to digest our food properly and to absorb the many other elements that we need to survive. Excessive vomiting can lead to a serious loss of chlorine in the body. This can lead to a dangerous imbalance of pH in the body, which can cause muscle weakness, loss of appetite, dehydration and coma.
It is easy to get enough chlorine from natural, unprocessed foods, and deficiencies of this important element are rare. Most Americans, however, consume massive amounts of salt in their diet. Table salt is a compound of sodium and chlorine (sodium chloride, or NaCl). This means most of us get much more chlorine than we really need.

Chromium (Cr)
When we think of chromium, our brains may generate images of everything from the shinny finish on our first bicycle to the brilliant chrome rally wheels on the ’66 Mustang GT. The last thing that comes to mind is a substance that we actually need to eat in order to stay healthy. Chromium, in fact, is an element that is essential to good human health. It does many important things in the body. Most significantly, it is a vital component of a molecule that works with insulin to stabilize blood sugar levels. In other words, it helps our bodies absorb energy from the food we eat and stabilizes the level of energy that we feel throughout the day.
Our bodies need sufficient quantities of chromium to make many of the large biological molecules that help us live. This vital element can also help increase muscle mass while reducing fat mass in our bodies. It helps cells, such as heart muscle cells absorb the energy they need to work properly.
Unfortunately, it is often difficult to get enough chromium in our diets. People who exercise frequently have especially high demands for this element. Scientists estimate that 90% of all Americans don't get enough chromium from their diet. Foods that are high in chromium include whole grain breads, brown rice, cheese and lean meats. Chromium is also in many (but not all) multi-vitamins and supplements, but the body absorbs chromium much better from food.

Cobalt (Co)
Cobalt is another element that is necessary for good human health. While cobalt has no specific function by itself, it forms the core of vitamin B-12. Without cobalt, Vitamin B-12 could not exist. The body uses this vitamin for numerous of purposes. B-12 is necessary for the normal formation of all cells, especially red blood cells. Vitamin B-12 also helps vitamin C perform its functions, and is necessary for the proper digestion of the food that we eat. Additionally, vitamin B-12 prevents nerve damage by contributing to the formation of the protective sheath that insulates nerve cells.
A deficiency of vitamin B-12 can cause our red blood cells to form improperly. This can prevent our red blood cells from carrying enough oxygen from our lungs to the different parts of our bodies, thus causing a condition called anemia. Symptoms of anemia include loss of energy, loss of appetite, and moodiness. B12 deficiency can also cause nerve cells to form incorrectly, resulting in irreversible nerve damage. This situation is characterized by symptoms such as delusions, eye disorders, dizziness, confusion and memory loss.
Unlike other B complex vitamins, vitamin B-12 can be stored in the body. Because of this, it is very easy to get enough of this important vitamin in your diet. Deficiencies of B-12 are rare in young people, but do occasionally occur in adults due to digestive disorders or poor absorption by the digestive system. Strict vegetarians are also at risk of B-12 deficiency, because vegetables do not contain this important vitamin. B-12 is only found in animal sources such as red meat, fish, eggs, cheese and milk. Fortunately for vegetarians, you can also get plenty of vitamin B-12 from most multi-vitamin pills.

Copper (Cu) - a micronutrient
Copper is an element that is very important for our good health. Actually, that may be understating the true importance of this element. Copper is critically important for dozens of body functions.
To begin with, copper is a major component of the oxygen carrying part of blood cells. Copper also helps protect our cells from being damaged by certain chemicals in our bodies. Copper, along with vitamin C, is important for keeping blood vessels and skin elastic and flexible. This important element is also required by the brain to form chemicals that keep us awake and alert. Copper also helps your body produce chemicals that regulate blood pressure, pulse, and healing. Current research is looking into other ways copper can affect human health, from protecting against cancer and heart disease, to boosting the immune system.
General symptoms of not getting enough copper in your diet include anemia (a condition in which your blood can’t supply enough oxygen to your body), arthritis (painful swelling of the joints), and many other medical problems.
Copper can be found in dried beans, almonds, broccoli, garlic, soybeans, peas, whole-wheat products, and seafood. Unfortunately, many people do not get enough copper in their diets. Also, eating food rich in fructose (sugars in fruit, and cornstarch) and taking mega-doses of vitamin C for long periods of time can keep your body from absorbing the copper in your food. This lack of copper intake by your body can cause the medical problems mentioned above, or it can even affect your life span.

Fluorine (F)
Fluorine is an element that the body uses to strengthen bones and teeth. This element differs from the other elements that the body needs because we get most of it from the water that we drink, not from the food that we eat. The form of fluorine that normally exists in nature, fluoride, is actually added to most drinking water supplies. In areas where fluoride is added to the drinking water, children get up to 70% fewer dental cavities than in areas where the drinking water is low in fluoride. As you may have noticed, it is also added to most brands of toothpaste for its ability to fight cavities.
But this important element is also valuable because it helps the body strengthen the bones in your body. Fluoride is the most important trace element affecting bones and teeth. In fact, fluoride is the only element known to single-handedly stimulate bone growth. Fluoride, along with large quantities of calcium, is a large part of what makes your bones strong. When the body does not receive enough fluoride, bones start to loose calcium, and then become weak and brittle. Fortunately, it is easy for us to get enough fluorine because of the fact that it is added to our drinking water. Other good sources of this key element include seafood, teas and toothpaste.

Germanium (Ge)
Germanium is a trace element that some believe is highly beneficial to good human health. In fact, germanium has many important medicinal properties. In the body, germanium attaches itself to oxygen molecules. This has the unexpected effect of making our bodies more effective at getting oxygen to the tissues in our body. The increased supply of oxygen in our bodies helps to improve our immune system. It also helps the body excrete harmful toxins.
The increased supply of oxygen in our bodies caused by germanium has many other exciting effects as well. Taking germanium supplements is effective in treating arthritis, food allergies, elevated cholesterol levels, high blood pressure, and even cancer. Germanium can also be used to control pain in the human body.
Perhaps the most exciting thing about germanium is that it can stimulate the human immune system to fight cancer cells. This is exciting for two reasons. First, and most obvious, it helps fight cancer - one of the most deadly diseases in the world. But more importantly, it is not toxic to human cells. In fact, germanium is completely harmless to human cells, even cancer cells. Since it works by stimulating our immune system, which fights the cancer, it doesn’t damage the rest of the body like many other cancer treatments. Testing of new cancer treatments with germanium are underway, and perhaps we will soon see new, less damaging, cancer treatments using the element germanium.

Hydrogen (H) - a macronutrient
It would be virtually impossible to understate the importance of this element to human life. First of all, water is a compound of hydrogen and oxygen (H2O). We can survive years, or at least months without getting most of the other elements that we need to survive. We can survive weeks without food, but we would die after only a few days without water. Water is incredibly important in our bodies. In fact, almost _ of our bodies are made of water. It dissolves other life-supporting substances and transports them to fluids in and around our cells. It is also a place in which important reactions take place in our bodies. Chemically, water is a remarkable substance and it’s many unique attributes make life possible. Hydrogen is obviously a critical component of water and minute chemical bonds called "hydrogen bonds" are what give water many of its unique attributes.
Also, hydrogen is practically always bound to the carbon that our bodies are constructed of. Without this arrangement, our bodies would be little more than a pile of atoms on the ground. Stomach acid is a compound of hydrogen and chlorine (hydrochloric acid, or HCl). Logically, hydrogen is extremely important in allowing us to digest our food properly and to absorb the many other elements that we need to survive. Finally, many chemical reactions that make life possible involve the hydrogen ion. Without this unique and important element, we simply couldn’t exist.

Iodine (I)
Iodine is an element that is required in very small amounts by the human body. You are probably already aware of some of the uses of this element. Iodine is found in a purple solution that we often put on scrapes and cuts to help our wounds heal faster by preventing them from getting infected. Also, backpackers and campers often add iodine to river and lake water to make it safe to drink.
But the most important thing about iodine is that it keeps our thyroid gland healthy. Most of the iodine in our bodies is stored in this organ, located in the base of your neck. The thyroid gland uses iodine to make chemicals that affect our growth, the way we development and how we burn the energy that we get from the food we eat. If we don’t get enough iodine in our diets, we can expect to have a loss of energy and to gain weight.
Iodine is found in large amounts in seafood, sea vegetables (for example, kelp), dairy products and iodized salt (table salt). It is easy to get enough of this element in your normal diet, and you probably get more than enough if you eat salty foods(with iodized salts, not salt substitutes) like potato chips or french fires.

Iron (Fe) - a micronutrient
The element iron has many functions in the body. This element is used by the body to make tendons and ligaments. Certain chemicals in our brain are controlled by the presence or absence of iron. It is also important for maintaining a healthy immune system and for digesting certain things in the food that we eat. In fact, plays a vitally important part of how our body obtains energy from our food.
The iron we obtain from our diet is an essential part of hemoglobin - the part of our blood that carries oxygen. Iron is essential for blood to work efficiently. If we don’t get enough iron in our diets, our blood won’t carry enough oxygen to our bodies and we can feel tired, have decreased alertness and attention span and our muscles may not function properly. This type of iron deficiency is not uncommon among athletes, especially long distance runners. This is frequently the cause of fatigue among these athletes. If the lack of iron in our bodies is severe, we can get "iron deficiency anemia", which essentially means that our blood won’t carry enough oxygen to our bodies so we can function normally. Iron deficiency anemia is probably the most common nutritional disease in the world, affecting at least five hundred million people.
Fortunately, it is easy to get enough iron in your food, if you eat a balanced diet. Many foods contain iron, and eating a wide range of foods can help most people meet their needs for this important element.

Magnesium (Mg) - a macronutrient
Magnesium is an element that is required by our bodies for numerous different functions. We need it for the proper growth, formation and function of our bones and muscles. In fact, magnesium and calcium even control how our muscles contract. Magnesium prevents some heart disorders and high blood pressure. Higher intake of magnesium is also associated with improved lung function. Our bodies use it to help convert our food into energy and it helps our bodies absorb calcium and potassium. This important element also helps our brains function normally. Magnesium even helps to prevent depression.
Magnesium is essential in allowing your body to control insulin levels in your blood. This means that it is very important in the amount of energy that your body has to operate. It is suspected that taking extra magnesium might be beneficial for those suffering from fatigue.
Taking extra magnesium is helpful for treating some medical conditions. Magnesium is sometimes injected into patients’ veins in emergency situations such as an acute heart attack or acute asthma attack. In non-emergency situations, magnesium is sometimes given to asthma sufferers in a pill form. It relaxes the muscles along the airway to the lungs, which allows asthma patients to breathe easier. Magnesium is effective in treating numerous heart / lung diseases and has been used for over 50 years.
Foods high in magnesium include fish, dairy products, lean meat, whole grains, seeds, and vegetables.

Manganese (Mn) - a micronutrient
Manganese is actually an extremely important element that the body uses for a variety of things. For instance, we use it to make chemicals that help us digest the food that we eat. Manganese also supports the immune system, regulates blood sugar levels, and is involved in the production of energy and cell reproduction. This important element is also important for bone growth. Additionally, manganese works with vitamin K to support blood clotting. Working with the B-complex vitamins, manganese helps to control the effects of stress while contributing to ones sense of well being.
Though it is extremely rare in humans, it is suspected that not getting enough manganese can cause poor bone formation, affect our fertility and the ability for our blood to clot. Birth defects can possibly even result when an expecting mother doesn’t get enough of this very important element. Some researchers are also looking into a link between poor manganese intake and higher skin cancer rates. The fact that manganese is so important to humans, yet deficiencies in humans are so rare, may indicate that humans have evolved ways to make sure that we don’t ever run out of this element in our bodies.
As is the case with most, if not all, elements, we can easily get enough manganese from a good balanced diet. Foods high in manganese include avocados, berries, nuts and seeds, egg yolks, whole grains, green leafy vegetables and legumes (such as peanuts, peas and beans).

Molybdenum (Mo) - a micronutrient
Molybdenum (pronounced mo-lyb-den-um) is necessary for good health, though in extremely small amounts. Molybdenum is found in all tissues of the human body, but tends to be the most concentrated in the liver, kidneys, skin and bones. It is required for the proper function of several chemicals in the human body. Some of these chemicals have the very important job of allowing the body to process the iron and nitrogen in our diets. Molybdenum is believed to be important in helping our cells grow. Also, small amounts of dietary molybdenum have been credited with promoting healthy teeth. Some evidence suggests that molybdenum might reduce the risk of some types of asthma attacks.
A deficiency of molybdenum in our diets can cause mouth and gum disorders and can contribute to getting cancer. A diet high in refined and processed foods can lead to a deficiency of molybdenum, resulting in anemia (lack of oxygen in the blood), loss of appetite and weight, and stunted growth in animals.
The amount of molybdenum in plant foods varies significantly and is dependent upon the mineral content of the soil that the plants were grown in. Nevertheless, the best sources of this mineral are beans, legumes (peanuts and peas), dark green leafy vegetables, and grains. Hard tap water can also supply molybdenum to the diet.

Nickel (Ni)
Nickel is known to be an essential trace element for several species of animals. Experimental research shows that when chickens and rats are fed a diet that lacks nickel, they develop liver problems. If they are fed a normal diet, the symptoms do not appear. Animals are not the only ones that need this element to function properly. Bacteria use nickel to make special chemicals called enzymes. These enzymes are necessary for bacteria to function properly.
Though many scientists suspect that nickel is necessary for good human health, it has not been proven. People with certain liver and kidney diseases are known to have low levels of nickel in their bodies. Also, excess nickel in the body is associated with a high incidence of heart disease, thyroid disease and cancer. In both of these cases, the significance of the amount of nickel in the body is unknown. Some scientists think that nickel affects hormones, cell membranes and chemicals called enzymes. Whatever the case, nickel certainly appears to affect human health, even though we do not know exactly how.
Good sources of nickel include chocolate, nuts, fruits and vegetables. Meats are typically low in this interesting element.

Nitrogen (N) - a macronutrient
Nitrogen is another important element. It plays an important role in digestion of food and growth. As you may know, almost 80% of the air we breathe is made up of nitrogen. But humans cannot use the nitrogen in the air we breathe, that nitrogen is in the wrong form. We have to get nitrogen, in a different form, from the food that we eat. Fortunately, there is plenty of nitrogen in food to nourish our bodies.
Nitrogen is found in large amounts in all kinds of food. Spaghetti, salads, breakfast cereal, hamburgers and even cookies have lots of nitrogen in the form that our bodies need. When your body digests this food and makes it into energy, the first step is to remove nitrogen atoms from the molecules in the food. While your body is busy digesting the rest of this food and making it into energy, these nitrogen atoms are already being used to help you grow. One specific time that this is especially important is during pregnancy. When a woman is pregnant, the nitrogen removed from food during digestion is needed to help the fetus to grow properly. By term, the mother and infant will have accumulated over a pound of nitrogen.
It is also worth noting that in the plant kingdom, nitrogen is one of the 3 main elements that make plant life possible. (Potassium and phosphorus are the other two, and you may hear them referred to collectively as N-P-K whenever talking about key plant nutrients.)

Oxygen (O) - a macronutrient
It may seem obvious that people need to breathe oxygen to survive, but plants need this element too. Many people think plants "breathe" carbon dioxide and "exhale" oxygen. But in reality, plants also "breathe" oxygen at certain times. Without oxygen, plants could not survive. Without plants, we wouldn’t have food to eat.
It is also worth mentioning that water is a compound of hydrogen and oxygen (H2O) and that water is absolutely necessary for virtually all life as we know it. Water is incredibly important in our bodies. In fact, more than 50% of our bodies are made of water. It dissolves other life-supporting substances and transports them to fluids in and around our cells. It is also a place in which important reactions take place in our bodies. Many people consider water to be the "blood of life".
When you consider the full importance of oxygen, it becomes clear that this versatile element is the single most important substance to life.

Phosphorus (P) - a macronutrient
Phosphorus is one of the most abundant minerals in the human body, second only to calcium. This essential mineral is required for the healthy formation of bones and teeth, and is necessary for our bodies to process many of the foods that we eat. It is also a part of the body's energy storage system, and helps with maintaining healthy blood sugar levels. Phosphorus is also found in substantial amounts in the nervous system. The regular contractions of the heart are dependant upon phosphorus, as are normal cell growth and repair.
Since phosphorus is found in almost all plant and animal food sources, a deficiency of this mineral is rarely seen. However, phosphorus deficiency can and does occur, particularly in people who take certain types of antacids for many years. Since phosphorus is important in maintaining the body’s energy system and proper blood sugar levels, it should seem logical that not getting enough of this mineral will affect the energy level in the entire body. Indeed, feeling easily fatigued, weak and having a decreased attention span can be symptoms of mild phosphate deficiency.
It is also worth noting that in the plant kingdom, phosphorus is one of the 3 main elements that make plant life possible. (Potassium and nitrogen are the other two, and you may hear them referred to collectively as N-P-K whenever talking about key plant nutrients.)
The human body must maintain a balance between magnesium phosphorus, and calcium. Excess intake of phosphorus can occur in people with diets high in processed foods, soft drinks, and meats, leading to osteoporosis.
The Recommended Dietary Allowances for phosphorus is 300 milligrams for infants, and between 800 and 1,200 milligrams for adults. It is estimated that Americans ingest on average between 1,500 and 1,600 milligrams of phosphorus per day, almost twice the recommended amount. Foods highest in phosphorus include asparagus, brewers yeast, dairy products, eggs, fish, dried fruit, meats, garlic, legumes, nuts and seeds, and whole grains.
Many antacids, which are widely used for treatment of peptic ulcer disease, gastritis (heart burn) and acid reflux, contain magnesium and aluminum, both of which bind to phosphate, preventing its absorption into the body.

Potassium (K) - a macronutrient
The element Potassium is an extremely important element in the human body. Our bodies are made up of millions of tiny cells, such as brain cells, skin cells, liver cells etc. These cells make up the different organs in our bodies, such as the brain, skin, or liver. Potassium is extremely important to cells, and without it, we could not survive.
Cells are the small building blocks of the human body. In order to work properly, cells need to let things enter and leave them. Cells have many ways by which they can control what (and how much) enters and leaves. Most of the ways that cells do this requires potassium. In fact, without potassium, cells loose control of what can enter and leave them. As you can imagine, this could be very bad. Imagine a nerve cell in your finger for a moment. Normally, it doesn’t really do very much. But when you touch something, it sends messages down a chain of many nerves to your brain that help you determine what it is that you just touched. When a nerve cell does this, it actually pumps out chemicals, which give the message to the next nerve cell and eventually to the brain. Potassium helps control the release of those chemicals. Without potassium, the nerve cell couldn’t send those messages to your brain.
But it is not just nerve cells that depend on potassium. Most, if not all, of our cells depend on it. Just think of it for a minute. Every time you flex your muscles, blink your eyes, yawn in chemistry class, eat lunch, or do anything, you are using potassium. This element is indeed a very important element in our bodies.
It is also worth noting that in the plant kingdom, potassium is one of the 3 main elements that make plant life possible. (Nitrogen and phosphorus are the other two, and you may hear them referred to collectively as N-P-K whenever talking about key plant nutrients.)

Selenium (Se)
Despite selenium’s reputation as a toxic heavy metal, this element is actually very important to good human health. Selenium is an important part of a molecule in the body that protects blood cells from certain damaging chemicals. Together with vitamin E, selenium helps our immune system produce antibodies, which is obviously an immensely important task. Selenium helps keep the pancreas and heart functioning properly. This remarkable element is also needed to make our tissues elastic. Imagine, for instance, if our skin wasn’t elastic; we’d have loose skin draping all over our bodies. It may be cool to have loose clothes draping all over our bodies, but people might make fun of you if you had that much loose skin. Sufficed to say that selenium is a very important element to our bodies.
A deficiency of this vital trace element has been linked to the development of leukemia, arthritis, and other diseases. Researchers have also found that the lower the concentration of selenium in the blood stream, the higher the risk of developing many types of cancer. In fact, some researchers tout selenium as being a powerful cancer-preventing substance. High selenium intake has also been correlated with a dramatically lower incidence of heart disease.
The amount of selenium in food is dependent on the amount of the element in the environment where the food is from. Fish, grains and brazil nuts are considered to be good dietary sources of selenium. However, in the current global marketplace it is difficult to know whether the food you eat comes from selenium-rich or selenium-poor growing areas. As with virtually all elements, it is easy to get enough selenium from a well balanced diet.

Silicon (Si)
If we reflect upon what we all know about silicon for a moment, some of us may recognize silicon as being the key component of sand. Others may think of computer chips; and there is no doubt a few that think of breast implants. Few of us would consider that silicon is something our bodies actually need to be healthy. Silicon is indeed a very common mineral that is required by our bodies. We use it, along with calcium, to grow and maintain strong bones. It is also important to the formation of connective tissues, like ligaments and tendons. Silicon is also important for the growth of hair, skin and fingernails. Unfortunately, despite the fact that silicon is important to the human body, there is comparatively little being done to learn more about why and exactly how it is important for good health.
It is possible that silicon is influential in preventing veins and arteries from getting hard and stiff, though there is no clear understanding of how this element affects artery hardening. Also, it is known that silicon reduces the effectiveness of aluminum in the body. It has been suggested that silicon may be able to delay or prevent Alzheimer’s disease. But once again, it is unclear how silicon may affect this degenerative disease of the brain. A form of silicon is actually a home remedy for problems with weakening bones, painful joints and aging skin, though there is no clear evidence that it actually helps such conditions.
Generally it is quite easy to get plenty of silicon in a normal diet and deficiencies are extremely rare. Foods rich in silicon include whole grain breads and cereals, alfalfa, beets, bell peppers, beans and peas.

Sodium (Na)
Sodium is an element that is vital to human life. Together with potassium and chlorine, it forms a very important part of blood plasma. Without sodium, our cells could not get the nutrients they need to survive. Sodium also allows our bodies to maintain the right blood chemistry and the correct amount of water in our blood. This element also allows our muscles to contract normally. Furthermore, our bodies need sodium to digest the food that we eat. Normal functioning of our nervous system also depends on this important element.
Having the proper amount of sodium in our blood is so important that our bodies have special ways to maintain the right levels of this important element. For instance, if you eat a bag of salty potato chips (salt is actually a compound of sodium and chlorine), your body will soon sense that there is too much sodium in your body. Your body’s first response will be to become thirsty. When you drink water, the sodium in your blood becomes diluted and then your kidneys can remove the excess sodium that you consumed when you ate the salty potato chips.
The foods that most Americans eat are very high in salt content (i.e. potato chips, french fries and popcorn). Salt is really a compound of sodium and chlorine. Therefore, most Americans consume far more sodium than our bodies actually need and it is uncommon that someone would not get enough of this element. One situation that a sodium deficiency can occur, however, is when you sweat a large amount from playing sports or exercising extensively. Your sweat contains a lot of sodium and if you sweat enough, you will loose too much sodium. This can lead to dehydration, weakness and mental confusion. Many athletes drink sports drinks that contain a lot of sodium, like Gatorade, to prevent this from happening.

Sulfur (S) - a macronutrient
Sis is an important element that is used in small amounts to help construct virtually all parts of the human body. Sulfur helps protect the cells in our bodies from environmental hazards such as air pollution and radiation. Consequently, sulfur slows down the aging process and extends our life span. Also, sulfur helps our liver function properly, helps us digest the food that we eat and then turn that food into energy. Sulfur is also important for helping our blood clot when we cut or bruise ourselves. Additionally, sulfur is an important part of vitamin B1 and insulin. Interestingly, sulfur is also an important part of a substance that keeps your skin supple and elastic. If you don’t think that is important, just imagine trying to get a date to the homecoming dance with stiff, loose skin hanging all over your body.
Fortunately, there is plenty of sulfur in the food that we eat and it is easy to get enough of this important element in our daily diets. There is no need to worry about getting too much sulfur in your diet. If you get more than your body needs, you just excrete it in your urine. Foods that have a lot of sulfur include meats, fish, dairy products, eggs and garlic.

Tin (Sn)
Tin is possibly an essential element for animals, but no specific role for tin in human health has been identified. Some scientists suspect that extremely small quantities of tin are necessary for some species of animals, such as rats, to grow and develop correctly. Some nutritional supplement retailers suggest that a deficiency in tin can cause baldness in humans, but that has not been proven. Actually, no specific function of any kind for tin has been identified in humans.

Titanium (Ti)
Very little has been written on the biological role of titanium. Titanium has no known biological use in humans, although it is known to act as a stimulant. In some plants, titanium is used in chemical energy production. Titanium is used in prosthetics because it won’t react with the biological tissues in the body.

Tungsten (W)
Opinions are mixed about the need for tungsten in plant and animal life processes, although it has been proved to be necessary for certain bacteria. This element has a small function in biological processes. Tungsten is used by certain non-oxygen consuming bacteria in extremely hot ocean environments, such as in hot ocean sediments and deep-sea ocean vents. The bacteria in these environments use tungsten to produce special chemicals called enzymes, which are necessary for certain life processes. Exactly how tungsten is used by these unique and interesting bacteria is quite complex and beyond the scope of this discussion.
It is not known if humans need tungsten for good health. Tungsten is thought to be used by a small number of enzymes in a fashion similar to molybdenum. Here’s how it might be important.
The enzymes described above are in a class of enzymes that perform important tasks for human health. However, the enzymes in this class that humans use incorporate molybdenum, not tungsten, into their structures. Some sources indicate that tungsten is important to humans. But their reasoning is faulty: (a) tungsten is in some of the enzymes of enzyme class "x" (b) some enzymes of class "x" are important to human health (c) therefore, tungsten is important to human health.

Vanadium (V)
Vanadium has recently been declared by some scientists to be essential for good human health. It is believed that vanadium is involved in helping the body convert some foods into energy. It has also been suggested that diabetics may benefit from vanadium when trying to stabilize blood sugar levels. This element is also thought to help bones and teeth form properly.
There is not a great deal of scientific knowledge as to the exact importance of vanadium. Actually, no specific symptoms of vanadium deficiency have been identified in human beings. It is possible that not getting enough of this element may affect the body’s ability to control blood sugar levels and contribute to developing diabetes or hypoglycemia (abnormally low blood sugar levels). Some scientists suspect that a deficiency of this mineral may increase the chance of getting kidney and heart disease. Some research has also shown that vanadium may slow the growth of tumors and provide protection against the development of breast cancer. But more research is clearly needed to determine its exact role in human health.
As is the case with most, if not all, of the biologically important elements, it is easy to get enough of this element from a healthy, balanced diet. Good sources of vanadium include seafood, mushrooms, olives, whole grain breads, carrots and vegetable oils.

Zinc (Zn) - a micronutrient
Zinc has been recognized as an essential trace element for plants, animals and humans for more than 70 years. Though the average adult body only contains between 2-3 grams of zinc (a paperclip weighs about one gram), this element has some very important functions. Zinc is involved in well over one hundred different reactions in the body. Some of these reactions help our bodies construct and maintain DNA, the molecule that controls how every single part of our bodies is made and works. Zinc is also needed for the growth and repair of tissues throughout our bodies. This extremely important element is used to form connective tissue like ligaments and tendons. Teeth, bones, nails, skin and hair could not grow without zinc. Zinc is widely considered by doctors to be one of the most important elements to a healthy immune system. This unique element is essential for the creation, release and use of hormones in the body. It helps developing fetuses grow correctly and our brains to work right. Additionally, our senses of sight, taste and smell depend on this element.
Not getting enough zinc can have serious effects on our health. Some of the symptoms of zinc deficiency include hair loss, mental apathy and damage to reproductive organs. Decreased growth rate and impaired mental capacity are other symptoms. Additionally, you can loose most of your senses of taste and smell, develop mental disorders and men can even become impotent without enough zinc.
Many factors affect how well our bodies absorb zinc in the food we eat, and at times it can be difficult to get enough zinc - even from a well balanced diet. Good sources of zinc include whole wheat bread, seafood and other animal meats.
Several other sources (US Geological Survey, United Nations FAO) list additional elements as having a role in plant and/or animal life processes. But no description of that "role" was discovered. Those More than 30 elements have a key function in helping plants and animals live and be healthy.
Everything around us is composed of chemical elements. Elements are the basic building blocks of our lives. Elements combine with one another in different proportions to form everything from the air that we breathe, to the wood that we use to build our homes, to our own bodies.
Our bodies use different chemical elements for different functions. For instance, our bodies use calcium to build strong bones and fluorine makes our teeth healthier. As our bodies consume these elements through daily functioning, we have to replace them in order to stay healthy and strong. The greatest source of these elements is through the food we eat. Because some of us do not always eat the right foods, we sometimes have to take dietary supplements, such as vitamins, to assure that we maintain the proper chemical balance in our bodies.
Some of the major elements that our bodies use to function properly are described in the following paragraphs. Some surprising minor elements are also described.
Aluminum (Al)
Until recently, aluminum was thought to be useless to life processes. It is now thought to be involved in the action of a small number of enzymes. For a technical explanation: "it may be involved in the action of enzymes such a succinic dehydrogenase and d-aminolevulinate dehydrase (involved in porphyrin synthesis)." I have no idea what that means.
Even if this element is necessary for some life function, the amount necessary is greatly exceeded by our incidental intake through our drinking water, food, deodorants and some antacids. Aluminum is relatively benign, and it is used in food additives and indigestion pills. It has been linked to Alzheimer's disease and the body has a hard time ridding itself of excess aluminum. Aluminum is somewhat more toxic to plants.

Arsenic (As)
Despite Arsenic’s reputation as a highly toxic substance, this element may actually be necessary for good health. Studies of animals such as chickens, rats, goats and pigs show that it is necessary for proper growth, development and reproduction. In these studies, the main symptom of not getting enough arsenic was retarded growth and development. It is suspected, but not known, that arsenic is necessary . It is thought to be necessary for the functioning of the nervous system and for people to grow properly. Since arsenic is present in our food and water, all humans have some arsenic in their bodies and a deficiency of this element in humans has apparently never been observed. An arsenic trioxide has been approved by the Food and Drug Administration to treat a rare and deadly form of leukemia called acute promyelocytic leukemia, or APL.

Boron (B) - a micronutrient
At first, boron may seem like an unimportant, uncommon and boring element. But boron is actually required by the body in very small amounts, and is necessary for good health. Though it is commonly known that calcium builds strong bones, boron is also important. Bones are not just the dead, white, stone-like things we see on skeletons. In our bodies bones are constantly breaking down and being rebuilt. They also have a constant blood supply and are very much "alive". Without small amounts of boron, bones would slowly break down and become brittle.
This element is also necessary to allow the brain to function properly. In fact, boron can increase mental alertness. According to a series of studies recently conducted by the US Department of Agriculture, low boron intakes by humans caused decreased brain activity. The studies showed that people on low boron diets also had lower brain performance on attention and short-term memory tests.
Our bodies also need boron in very small amounts to allow calcium, magnesium and phosphorus to function properly. So in a sense, boron is also necessary for many other body functions and we could not survive without it.

Bromine (Br)
This is another element that is probably not necessary for good health and no deficiency of this element has ever been documented. Bromine is suspected to be an essential trace element in red algae and possibly humans. No specific role for this element in human health has been identified. Bromine is found in the mollusk pigment "royal purple", but it’s purpose in that pigment is not known.

Cadmium (Cd)
Mixed opinions on cadmium. While it is definitely believed to not be essential for plant and animal life processes, some believe cadmium is a trace element with some necessary role in life processes. Although its need and use are not currently understood. It is thought to be involved with the metabolism Its status as an essential trace element remains unclear.

Calcium (Ca) - a macronutrient
Calcium is an extremely important element in the human body. It is one of the most abundant elements in our bodies and accounts for 2 to 3 pounds of our total body weight. Most of us know that calcium is important in building and maintaining strong bones and teeth, but it is also important for many other things. It helps control things like muscle growth and the electrical impulses in your brain. This vital element is also necessary to maintain proper blood pressure and make blood clot when you get cut. Calcium also enables other molecules to digest food and make energy for the body. Increasing calcium intake in our diet is believed to lower high blood pressure and prevent heart disease. It is also used to treat arthritis.
When we don’t get enough calcium, many things happen in our bodies. It is possible to get leg cramps, muscle spasms, our bones may become brittle and even we may even have an increased risk of getting colon cancer. Also, when we don’t get enough calcium in our diets, our bodies will actually use the calcium that we have stored in our bones. This makes the bones thinner and more brittle. In growing children and teenagers the bones may not develop fully and the person can enter adulthood with brittle bones. Further calcium deficiency can lead to serious problems.
Therefore, it is extremely important to get enough calcium in your diet. Unfortunately, that is not always easy to do. Most Americans don’t get enough from their diets. But eating a good balanced diet, including drinking milk on a daily basis, should get you enough calcium.

Carbon (C) - a macronutrient
The element carbon is perhaps the single most important element to life. Virtually every part of our bodies is made with large amounts of this element. The carbon atom is ideal to build big biological molecules. The carbon atom can be thought of as a basic building block. These building blocks can be attached to each other to form long chains, or they can be attached to other elements.
This can be difficult to imagine at first, but it may help to think about building with Legos. You can think of carbon as a bunch of red legos attached together to form one long chain of legos. Now, you can imagine sticking yellow, blue and green legos across the tops of the red (carbon) legos. These other colors represent other elements like oxygen, nitrogen or hydrogen. As you stick more and more of these yellow, blue and green legos to the red chain, it would start to look like a skeleton of legos with a "spine" of red legos and "bones" of yellow, blue and green legos. This is a lot like the way that big molecules are made in the body. Without carbon, these big molecules could not be built.
Now, virtually every part of your body is made up of these big molecules that are based around chains of carbon atoms. This is the reason we are known as "carbon based life forms". Without carbon, our bodies would just be a big pile of loose atoms with no way to be built into a person.

Chlorine (Cl) - a micronutrient
Anyone who has ever swallowed a mouthful of water at a swimming pool would probably tell you that chlorine is one of the most unpleasant things they have ever swallowed and they wouldn’t mind if they never ingest chlorine ever again. This element, however, is actually essential for humans to live - we would die without it. Chlorine is found throughout the body; in the blood, in the fluid inside cells and in the fluid between cells.
Along with sodium and potassium, chlorine carries an electrical charge when dissolved in body fluids. This is why these elements are termed "electrolytes". The electrical charge that these elements carry is what allows nerve cells to work. Chlorine also works with potassium and sodium to regulate the amount of fluids in the body and to regulate pH in the body. This vital element also helps muscles flex and relax normally.
Stomach acid is a compound of hydrogen and chlorine (hydrochloric acid, or HCl). Logically, chlorine is extremely important in allowing us to digest our food properly and to absorb the many other elements that we need to survive. Excessive vomiting can lead to a serious loss of chlorine in the body. This can lead to a dangerous imbalance of pH in the body, which can cause muscle weakness, loss of appetite, dehydration and coma.
It is easy to get enough chlorine from natural, unprocessed foods, and deficiencies of this important element are rare. Most Americans, however, consume massive amounts of salt in their diet. Table salt is a compound of sodium and chlorine (sodium chloride, or NaCl). This means most of us get much more chlorine than we really need.

Chromium (Cr)
When we think of chromium, our brains may generate images of everything from the shinny finish on our first bicycle to the brilliant chrome rally wheels on the ’66 Mustang GT. The last thing that comes to mind is a substance that we actually need to eat in order to stay healthy. Chromium, in fact, is an element that is essential to good human health. It does many important things in the body. Most significantly, it is a vital component of a molecule that works with insulin to stabilize blood sugar levels. In other words, it helps our bodies absorb energy from the food we eat and stabilizes the level of energy that we feel throughout the day.
Our bodies need sufficient quantities of chromium to make many of the large biological molecules that help us live. This vital element can also help increase muscle mass while reducing fat mass in our bodies. It helps cells, such as heart muscle cells absorb the energy they need to work properly.
Unfortunately, it is often difficult to get enough chromium in our diets. People who exercise frequently have especially high demands for this element. Scientists estimate that 90% of all Americans don't get enough chromium from their diet. Foods that are high in chromium include whole grain breads, brown rice, cheese and lean meats. Chromium is also in many (but not all) multi-vitamins and supplements, but the body absorbs chromium much better from food.

Cobalt (Co)
Cobalt is another element that is necessary for good human health. While cobalt has no specific function by itself, it forms the core of vitamin B-12. Without cobalt, Vitamin B-12 could not exist. The body uses this vitamin for numerous of purposes. B-12 is necessary for the normal formation of all cells, especially red blood cells. Vitamin B-12 also helps vitamin C perform its functions, and is necessary for the proper digestion of the food that we eat. Additionally, vitamin B-12 prevents nerve damage by contributing to the formation of the protective sheath that insulates nerve cells.
A deficiency of vitamin B-12 can cause our red blood cells to form improperly. This can prevent our red blood cells from carrying enough oxygen from our lungs to the different parts of our bodies, thus causing a condition called anemia. Symptoms of anemia include loss of energy, loss of appetite, and moodiness. B12 deficiency can also cause nerve cells to form incorrectly, resulting in irreversible nerve damage. This situation is characterized by symptoms such as delusions, eye disorders, dizziness, confusion and memory loss.
Unlike other B complex vitamins, vitamin B-12 can be stored in the body. Because of this, it is very easy to get enough of this important vitamin in your diet. Deficiencies of B-12 are rare in young people, but do occasionally occur in adults due to digestive disorders or poor absorption by the digestive system. Strict vegetarians are also at risk of B-12 deficiency, because vegetables do not contain this important vitamin. B-12 is only found in animal sources such as red meat, fish, eggs, cheese and milk. Fortunately for vegetarians, you can also get plenty of vitamin B-12 from most multi-vitamin pills.

Copper (Cu) - a micronutrient
Copper is an element that is very important for our good health. Actually, that may be understating the true importance of this element. Copper is critically important for dozens of body functions.
To begin with, copper is a major component of the oxygen carrying part of blood cells. Copper also helps protect our cells from being damaged by certain chemicals in our bodies. Copper, along with vitamin C, is important for keeping blood vessels and skin elastic and flexible. This important element is also required by the brain to form chemicals that keep us awake and alert. Copper also helps your body produce chemicals that regulate blood pressure, pulse, and healing. Current research is looking into other ways copper can affect human health, from protecting against cancer and heart disease, to boosting the immune system.
General symptoms of not getting enough copper in your diet include anemia (a condition in which your blood can’t supply enough oxygen to your body), arthritis (painful swelling of the joints), and many other medical problems.
Copper can be found in dried beans, almonds, broccoli, garlic, soybeans, peas, whole-wheat products, and seafood. Unfortunately, many people do not get enough copper in their diets. Also, eating food rich in fructose (sugars in fruit, and cornstarch) and taking mega-doses of vitamin C for long periods of time can keep your body from absorbing the copper in your food. This lack of copper intake by your body can cause the medical problems mentioned above, or it can even affect your life span.

Fluorine (F)
Fluorine is an element that the body uses to strengthen bones and teeth. This element differs from the other elements that the body needs because we get most of it from the water that we drink, not from the food that we eat. The form of fluorine that normally exists in nature, fluoride, is actually added to most drinking water supplies. In areas where fluoride is added to the drinking water, children get up to 70% fewer dental cavities than in areas where the drinking water is low in fluoride. As you may have noticed, it is also added to most brands of toothpaste for its ability to fight cavities.
But this important element is also valuable because it helps the body strengthen the bones in your body. Fluoride is the most important trace element affecting bones and teeth. In fact, fluoride is the only element known to single-handedly stimulate bone growth. Fluoride, along with large quantities of calcium, is a large part of what makes your bones strong. When the body does not receive enough fluoride, bones start to loose calcium, and then become weak and brittle. Fortunately, it is easy for us to get enough fluorine because of the fact that it is added to our drinking water. Other good sources of this key element include seafood, teas and toothpaste.

Germanium (Ge)
Germanium is a trace element that some believe is highly beneficial to good human health. In fact, germanium has many important medicinal properties. In the body, germanium attaches itself to oxygen molecules. This has the unexpected effect of making our bodies more effective at getting oxygen to the tissues in our body. The increased supply of oxygen in our bodies helps to improve our immune system. It also helps the body excrete harmful toxins.
The increased supply of oxygen in our bodies caused by germanium has many other exciting effects as well. Taking germanium supplements is effective in treating arthritis, food allergies, elevated cholesterol levels, high blood pressure, and even cancer. Germanium can also be used to control pain in the human body.
Perhaps the most exciting thing about germanium is that it can stimulate the human immune system to fight cancer cells. This is exciting for two reasons. First, and most obvious, it helps fight cancer - one of the most deadly diseases in the world. But more importantly, it is not toxic to human cells. In fact, germanium is completely harmless to human cells, even cancer cells. Since it works by stimulating our immune system, which fights the cancer, it doesn’t damage the rest of the body like many other cancer treatments. Testing of new cancer treatments with germanium are underway, and perhaps we will soon see new, less damaging, cancer treatments using the element germanium.

Hydrogen (H) - a macronutrient
It would be virtually impossible to understate the importance of this element to human life. First of all, water is a compound of hydrogen and oxygen (H2O). We can survive years, or at least months without getting most of the other elements that we need to survive. We can survive weeks without food, but we would die after only a few days without water. Water is incredibly important in our bodies. In fact, almost _ of our bodies are made of water. It dissolves other life-supporting substances and transports them to fluids in and around our cells. It is also a place in which important reactions take place in our bodies. Chemically, water is a remarkable substance and it’s many unique attributes make life possible. Hydrogen is obviously a critical component of water and minute chemical bonds called "hydrogen bonds" are what give water many of its unique attributes.
Also, hydrogen is practically always bound to the carbon that our bodies are constructed of. Without this arrangement, our bodies would be little more than a pile of atoms on the ground. Stomach acid is a compound of hydrogen and chlorine (hydrochloric acid, or HCl). Logically, hydrogen is extremely important in allowing us to digest our food properly and to absorb the many other elements that we need to survive. Finally, many chemical reactions that make life possible involve the hydrogen ion. Without this unique and important element, we simply couldn’t exist.

Iodine (I)
Iodine is an element that is required in very small amounts by the human body. You are probably already aware of some of the uses of this element. Iodine is found in a purple solution that we often put on scrapes and cuts to help our wounds heal faster by preventing them from getting infected. Also, backpackers and campers often add iodine to river and lake water to make it safe to drink.
But the most important thing about iodine is that it keeps our thyroid gland healthy. Most of the iodine in our bodies is stored in this organ, located in the base of your neck. The thyroid gland uses iodine to make chemicals that affect our growth, the way we development and how we burn the energy that we get from the food we eat. If we don’t get enough iodine in our diets, we can expect to have a loss of energy and to gain weight.
Iodine is found in large amounts in seafood, sea vegetables (for example, kelp), dairy products and iodized salt (table salt). It is easy to get enough of this element in your normal diet, and you probably get more than enough if you eat salty foods(with iodized salts, not salt substitutes) like potato chips or french fires.

Iron (Fe) - a micronutrient
The element iron has many functions in the body. This element is used by the body to make tendons and ligaments. Certain chemicals in our brain are controlled by the presence or absence of iron. It is also important for maintaining a healthy immune system and for digesting certain things in the food that we eat. In fact, plays a vitally important part of how our body obtains energy from our food.
The iron we obtain from our diet is an essential part of hemoglobin - the part of our blood that carries oxygen. Iron is essential for blood to work efficiently. If we don’t get enough iron in our diets, our blood won’t carry enough oxygen to our bodies and we can feel tired, have decreased alertness and attention span and our muscles may not function properly. This type of iron deficiency is not uncommon among athletes, especially long distance runners. This is frequently the cause of fatigue among these athletes. If the lack of iron in our bodies is severe, we can get "iron deficiency anemia", which essentially means that our blood won’t carry enough oxygen to our bodies so we can function normally. Iron deficiency anemia is probably the most common nutritional disease in the world, affecting at least five hundred million people.
Fortunately, it is easy to get enough iron in your food, if you eat a balanced diet. Many foods contain iron, and eating a wide range of foods can help most people meet their needs for this important element.

Magnesium (Mg) - a macronutrient
Magnesium is an element that is required by our bodies for numerous different functions. We need it for the proper growth, formation and function of our bones and muscles. In fact, magnesium and calcium even control how our muscles contract. Magnesium prevents some heart disorders and high blood pressure. Higher intake of magnesium is also associated with improved lung function. Our bodies use it to help convert our food into energy and it helps our bodies absorb calcium and potassium. This important element also helps our brains function normally. Magnesium even helps to prevent depression.
Magnesium is essential in allowing your body to control insulin levels in your blood. This means that it is very important in the amount of energy that your body has to operate. It is suspected that taking extra magnesium might be beneficial for those suffering from fatigue.
Taking extra magnesium is helpful for treating some medical conditions. Magnesium is sometimes injected into patients’ veins in emergency situations such as an acute heart attack or acute asthma attack. In non-emergency situations, magnesium is sometimes given to asthma sufferers in a pill form. It relaxes the muscles along the airway to the lungs, which allows asthma patients to breathe easier. Magnesium is effective in treating numerous heart / lung diseases and has been used for over 50 years.
Foods high in magnesium include fish, dairy products, lean meat, whole grains, seeds, and vegetables.

Manganese (Mn) - a micronutrient
Manganese is actually an extremely important element that the body uses for a variety of things. For instance, we use it to make chemicals that help us digest the food that we eat. Manganese also supports the immune system, regulates blood sugar levels, and is involved in the production of energy and cell reproduction. This important element is also important for bone growth. Additionally, manganese works with vitamin K to support blood clotting. Working with the B-complex vitamins, manganese helps to control the effects of stress while contributing to ones sense of well being.
Though it is extremely rare in humans, it is suspected that not getting enough manganese can cause poor bone formation, affect our fertility and the ability for our blood to clot. Birth defects can possibly even result when an expecting mother doesn’t get enough of this very important element. Some researchers are also looking into a link between poor manganese intake and higher skin cancer rates. The fact that manganese is so important to humans, yet deficiencies in humans are so rare, may indicate that humans have evolved ways to make sure that we don’t ever run out of this element in our bodies.
As is the case with most, if not all, elements, we can easily get enough manganese from a good balanced diet. Foods high in manganese include avocados, berries, nuts and seeds, egg yolks, whole grains, green leafy vegetables and legumes (such as peanuts, peas and beans).

Molybdenum (Mo) - a micronutrient
Molybdenum (pronounced mo-lyb-den-um) is necessary for good health, though in extremely small amounts. Molybdenum is found in all tissues of the human body, but tends to be the most concentrated in the liver, kidneys, skin and bones. It is required for the proper function of several chemicals in the human body. Some of these chemicals have the very important job of allowing the body to process the iron and nitrogen in our diets. Molybdenum is believed to be important in helping our cells grow. Also, small amounts of dietary molybdenum have been credited with promoting healthy teeth. Some evidence suggests that molybdenum might reduce the risk of some types of asthma attacks.
A deficiency of molybdenum in our diets can cause mouth and gum disorders and can contribute to getting cancer. A diet high in refined and processed foods can lead to a deficiency of molybdenum, resulting in anemia (lack of oxygen in the blood), loss of appetite and weight, and stunted growth in animals.
The amount of molybdenum in plant foods varies significantly and is dependent upon the mineral content of the soil that the plants were grown in. Nevertheless, the best sources of this mineral are beans, legumes (peanuts and peas), dark green leafy vegetables, and grains. Hard tap water can also supply molybdenum to the diet.

Nickel (Ni)
Nickel is known to be an essential trace element for several species of animals. Experimental research shows that when chickens and rats are fed a diet that lacks nickel, they develop liver problems. If they are fed a normal diet, the symptoms do not appear. Animals are not the only ones that need this element to function properly. Bacteria use nickel to make special chemicals called enzymes. These enzymes are necessary for bacteria to function properly.
Though many scientists suspect that nickel is necessary for good human health, it has not been proven. People with certain liver and kidney diseases are known to have low levels of nickel in their bodies. Also, excess nickel in the body is associated with a high incidence of heart disease, thyroid disease and cancer. In both of these cases, the significance of the amount of nickel in the body is unknown. Some scientists think that nickel affects hormones, cell membranes and chemicals called enzymes. Whatever the case, nickel certainly appears to affect human health, even though we do not know exactly how.
Good sources of nickel include chocolate, nuts, fruits and vegetables. Meats are typically low in this interesting element.

Nitrogen (N) - a macronutrient
Nitrogen is another important element. It plays an important role in digestion of food and growth. As you may know, almost 80% of the air we breathe is made up of nitrogen. But humans cannot use the nitrogen in the air we breathe, that nitrogen is in the wrong form. We have to get nitrogen, in a different form, from the food that we eat. Fortunately, there is plenty of nitrogen in food to nourish our bodies.
Nitrogen is found in large amounts in all kinds of food. Spaghetti, salads, breakfast cereal, hamburgers and even cookies have lots of nitrogen in the form that our bodies need. When your body digests this food and makes it into energy, the first step is to remove nitrogen atoms from the molecules in the food. While your body is busy digesting the rest of this food and making it into energy, these nitrogen atoms are already being used to help you grow. One specific time that this is especially important is during pregnancy. When a woman is pregnant, the nitrogen removed from food during digestion is needed to help the fetus to grow properly. By term, the mother and infant will have accumulated over a pound of nitrogen.
It is also worth noting that in the plant kingdom, nitrogen is one of the 3 main elements that make plant life possible. (Potassium and phosphorus are the other two, and you may hear them referred to collectively as N-P-K whenever talking about key plant nutrients.)

Oxygen (O) - a macronutrient
It may seem obvious that people need to breathe oxygen to survive, but plants need this element too. Many people think plants "breathe" carbon dioxide and "exhale" oxygen. But in reality, plants also "breathe" oxygen at certain times. Without oxygen, plants could not survive. Without plants, we wouldn’t have food to eat.
It is also worth mentioning that water is a compound of hydrogen and oxygen (H2O) and that water is absolutely necessary for virtually all life as we know it. Water is incredibly important in our bodies. In fact, more than 50% of our bodies are made of water. It dissolves other life-supporting substances and transports them to fluids in and around our cells. It is also a place in which important reactions take place in our bodies. Many people consider water to be the "blood of life".
When you consider the full importance of oxygen, it becomes clear that this versatile element is the single most important substance to life.

Phosphorus (P) - a macronutrient
Phosphorus is one of the most abundant minerals in the human body, second only to calcium. This essential mineral is required for the healthy formation of bones and teeth, and is necessary for our bodies to process many of the foods that we eat. It is also a part of the body's energy storage system, and helps with maintaining healthy blood sugar levels. Phosphorus is also found in substantial amounts in the nervous system. The regular contractions of the heart are dependant upon phosphorus, as are normal cell growth and repair.
Since phosphorus is found in almost all plant and animal food sources, a deficiency of this mineral is rarely seen. However, phosphorus deficiency can and does occur, particularly in people who take certain types of antacids for many years. Since phosphorus is important in maintaining the body’s energy system and proper blood sugar levels, it should seem logical that not getting enough of this mineral will affect the energy level in the entire body. Indeed, feeling easily fatigued, weak and having a decreased attention span can be symptoms of mild phosphate deficiency.
It is also worth noting that in the plant kingdom, phosphorus is one of the 3 main elements that make plant life possible. (Potassium and nitrogen are the other two, and you may hear them referred to collectively as N-P-K whenever talking about key plant nutrients.)
The human body must maintain a balance between magnesium phosphorus, and calcium. Excess intake of phosphorus can occur in people with diets high in processed foods, soft drinks, and meats, leading to osteoporosis.
The Recommended Dietary Allowances for phosphorus is 300 milligrams for infants, and between 800 and 1,200 milligrams for adults. It is estimated that Americans ingest on average between 1,500 and 1,600 milligrams of phosphorus per day, almost twice the recommended amount. Foods highest in phosphorus include asparagus, brewers yeast, dairy products, eggs, fish, dried fruit, meats, garlic, legumes, nuts and seeds, and whole grains.
Many antacids, which are widely used for treatment of peptic ulcer disease, gastritis (heart burn) and acid reflux, contain magnesium and aluminum, both of which bind to phosphate, preventing its absorption into the body.

Potassium (K) - a macronutrient
The element Potassium is an extremely important element in the human body. Our bodies are made up of millions of tiny cells, such as brain cells, skin cells, liver cells etc. These cells make up the different organs in our bodies, such as the brain, skin, or liver. Potassium is extremely important to cells, and without it, we could not survive.
Cells are the small building blocks of the human body. In order to work properly, cells need to let things enter and leave them. Cells have many ways by which they can control what (and how much) enters and leaves. Most of the ways that cells do this requires potassium. In fact, without potassium, cells loose control of what can enter and leave them. As you can imagine, this could be very bad. Imagine a nerve cell in your finger for a moment. Normally, it doesn’t really do very much. But when you touch something, it sends messages down a chain of many nerves to your brain that help you determine what it is that you just touched. When a nerve cell does this, it actually pumps out chemicals, which give the message to the next nerve cell and eventually to the brain. Potassium helps control the release of those chemicals. Without potassium, the nerve cell couldn’t send those messages to your brain.
But it is not just nerve cells that depend on potassium. Most, if not all, of our cells depend on it. Just think of it for a minute. Every time you flex your muscles, blink your eyes, yawn in chemistry class, eat lunch, or do anything, you are using potassium. This element is indeed a very important element in our bodies.
It is also worth noting that in the plant kingdom, potassium is one of the 3 main elements that make plant life possible. (Nitrogen and phosphorus are the other two, and you may hear them referred to collectively as N-P-K whenever talking about key plant nutrients.)

Selenium (Se)
Despite selenium’s reputation as a toxic heavy metal, this element is actually very important to good human health. Selenium is an important part of a molecule in the body that protects blood cells from certain damaging chemicals. Together with vitamin E, selenium helps our immune system produce antibodies, which is obviously an immensely important task. Selenium helps keep the pancreas and heart functioning properly. This remarkable element is also needed to make our tissues elastic. Imagine, for instance, if our skin wasn’t elastic; we’d have loose skin draping all over our bodies. It may be cool to have loose clothes draping all over our bodies, but people might make fun of you if you had that much loose skin. Sufficed to say that selenium is a very important element to our bodies.
A deficiency of this vital trace element has been linked to the development of leukemia, arthritis, and other diseases. Researchers have also found that the lower the concentration of selenium in the blood stream, the higher the risk of developing many types of cancer. In fact, some researchers tout selenium as being a powerful cancer-preventing substance. High selenium intake has also been correlated with a dramatically lower incidence of heart disease.
The amount of selenium in food is dependent on the amount of the element in the environment where the food is from. Fish, grains and brazil nuts are considered to be good dietary sources of selenium. However, in the current global marketplace it is difficult to know whether the food you eat comes from selenium-rich or selenium-poor growing areas. As with virtually all elements, it is easy to get enough selenium from a well balanced diet.

Silicon (Si)
If we reflect upon what we all know about silicon for a moment, some of us may recognize silicon as being the key component of sand. Others may think of computer chips; and there is no doubt a few that think of breast implants. Few of us would consider that silicon is something our bodies actually need to be healthy. Silicon is indeed a very common mineral that is required by our bodies. We use it, along with calcium, to grow and maintain strong bones. It is also important to the formation of connective tissues, like ligaments and tendons. Silicon is also important for the growth of hair, skin and fingernails. Unfortunately, despite the fact that silicon is important to the human body, there is comparatively little being done to learn more about why and exactly how it is important for good health.
It is possible that silicon is influential in preventing veins and arteries from getting hard and stiff, though there is no clear understanding of how this element affects artery hardening. Also, it is known that silicon reduces the effectiveness of aluminum in the body. It has been suggested that silicon may be able to delay or prevent Alzheimer’s disease. But once again, it is unclear how silicon may affect this degenerative disease of the brain. A form of silicon is actually a home remedy for problems with weakening bones, painful joints and aging skin, though there is no clear evidence that it actually helps such conditions.
Generally it is quite easy to get plenty of silicon in a normal diet and deficiencies are extremely rare. Foods rich in silicon include whole grain breads and cereals, alfalfa, beets, bell peppers, beans and peas.

Sodium (Na)
Sodium is an element that is vital to human life. Together with potassium and chlorine, it forms a very important part of blood plasma. Without sodium, our cells could not get the nutrients they need to survive. Sodium also allows our bodies to maintain the right blood chemistry and the correct amount of water in our blood. This element also allows our muscles to contract normally. Furthermore, our bodies need sodium to digest the food that we eat. Normal functioning of our nervous system also depends on this important element.
Having the proper amount of sodium in our blood is so important that our bodies have special ways to maintain the right levels of this important element. For instance, if you eat a bag of salty potato chips (salt is actually a compound of sodium and chlorine), your body will soon sense that there is too much sodium in your body. Your body’s first response will be to become thirsty. When you drink water, the sodium in your blood becomes diluted and then your kidneys can remove the excess sodium that you consumed when you ate the salty potato chips.
The foods that most Americans eat are very high in salt content (i.e. potato chips, french fries and popcorn). Salt is really a compound of sodium and chlorine. Therefore, most Americans consume far more sodium than our bodies actually need and it is uncommon that someone would not get enough of this element. One situation that a sodium deficiency can occur, however, is when you sweat a large amount from playing sports or exercising extensively. Your sweat contains a lot of sodium and if you sweat enough, you will loose too much sodium. This can lead to dehydration, weakness and mental confusion. Many athletes drink sports drinks that contain a lot of sodium, like Gatorade, to prevent this from happening.

Sulfur (S) - a macronutrient
Sis is an important element that is used in small amounts to help construct virtually all parts of the human body. Sulfur helps protect the cells in our bodies from environmental hazards such as air pollution and radiation. Consequently, sulfur slows down the aging process and extends our life span. Also, sulfur helps our liver function properly, helps us digest the food that we eat and then turn that food into energy. Sulfur is also important for helping our blood clot when we cut or bruise ourselves. Additionally, sulfur is an important part of vitamin B1 and insulin. Interestingly, sulfur is also an important part of a substance that keeps your skin supple and elastic. If you don’t think that is important, just imagine trying to get a date to the homecoming dance with stiff, loose skin hanging all over your body.
Fortunately, there is plenty of sulfur in the food that we eat and it is easy to get enough of this important element in our daily diets. There is no need to worry about getting too much sulfur in your diet. If you get more than your body needs, you just excrete it in your urine. Foods that have a lot of sulfur include meats, fish, dairy products, eggs and garlic.

Tin (Sn)
Tin is possibly an essential element for animals, but no specific role for tin in human health has been identified. Some scientists suspect that extremely small quantities of tin are necessary for some species of animals, such as rats, to grow and develop correctly. Some nutritional supplement retailers suggest that a deficiency in tin can cause baldness in humans, but that has not been proven. Actually, no specific function of any kind for tin has been identified in humans.

Titanium (Ti)
Very little has been written on the biological role of titanium. Titanium has no known biological use in humans, although it is known to act as a stimulant. In some plants, titanium is used in chemical energy production. Titanium is used in prosthetics because it won’t react with the biological tissues in the body.

Tungsten (W)
Opinions are mixed about the need for tungsten in plant and animal life processes, although it has been proved to be necessary for certain bacteria. This element has a small function in biological processes. Tungsten is used by certain non-oxygen consuming bacteria in extremely hot ocean environments, such as in hot ocean sediments and deep-sea ocean vents. The bacteria in these environments use tungsten to produce special chemicals called enzymes, which are necessary for certain life processes. Exactly how tungsten is used by these unique and interesting bacteria is quite complex and beyond the scope of this discussion.
It is not known if humans need tungsten for good health. Tungsten is thought to be used by a small number of enzymes in a fashion similar to molybdenum. Here’s how it might be important.
The enzymes described above are in a class of enzymes that perform important tasks for human health. However, the enzymes in this class that humans use incorporate molybdenum, not tungsten, into their structures. Some sources indicate that tungsten is important to humans. But their reasoning is faulty: (a) tungsten is in some of the enzymes of enzyme class "x" (b) some enzymes of class "x" are important to human health (c) therefore, tungsten is important to human health.

Vanadium (V)
Vanadium has recently been declared by some scientists to be essential for good human health. It is believed that vanadium is involved in helping the body convert some foods into energy. It has also been suggested that diabetics may benefit from vanadium when trying to stabilize blood sugar levels. This element is also thought to help bones and teeth form properly.
There is not a great deal of scientific knowledge as to the exact importance of vanadium. Actually, no specific symptoms of vanadium deficiency have been identified in human beings. It is possible that not getting enough of this element may affect the body’s ability to control blood sugar levels and contribute to developing diabetes or hypoglycemia (abnormally low blood sugar levels). Some scientists suspect that a deficiency of this mineral may increase the chance of getting kidney and heart disease. Some research has also shown that vanadium may slow the growth of tumors and provide protection against the development of breast cancer. But more research is clearly needed to determine its exact role in human health.
As is the case with most, if not all, of the biologically important elements, it is easy to get enough of this element from a healthy, balanced diet. Good sources of vanadium include seafood, mushrooms, olives, whole grain breads, carrots and vegetable oils.

Zinc (Zn) - a micronutrient
Zinc has been recognized as an essential trace element for plants, animals and humans for more than 70 years. Though the average adult body only contains between 2-3 grams of zinc (a paperclip weighs about one gram), this element has some very important functions. Zinc is involved in well over one hundred different reactions in the body. Some of these reactions help our bodies construct and maintain DNA, the molecule that controls how every single part of our bodies is made and works. Zinc is also needed for the growth and repair of tissues throughout our bodies. This extremely important element is used to form connective tissue like ligaments and tendons. Teeth, bones, nails, skin and hair could not grow without zinc. Zinc is widely considered by doctors to be one of the most important elements to a healthy immune system. This unique element is essential for the creation, release and use of hormones in the body. It helps developing fetuses grow correctly and our brains to work right. Additionally, our senses of sight, taste and smell depend on this element.
Not getting enough zinc can have serious effects on our health. Some of the symptoms of zinc deficiency include hair loss, mental apathy and damage to reproductive organs. Decreased growth rate and impaired mental capacity are other symptoms. Additionally, you can loose most of your senses of taste and smell, develop mental disorders and men can even become impotent without enough zinc.
Many factors affect how well our bodies absorb zinc in the food we eat, and at times it can be difficult to get enough zinc - even from a well balanced diet. Good sources of zinc include whole wheat bread, seafood and other animal meats.
Several other sources (US Geological Survey, United Nations FAO) list additional elements as having a role in plant and/or animal life processes. But no description of that "role" was discovered. Those elements are: Strontium, Lithium, Barium, Rubidium, Cesium, and Platinum (for plants).ments are: Strontium, Lithium, Barium, Rubidium, Cesium, and Platinum (for plants).

Important Elements in the Environment and Industry

Elements are important to us. We utilize them to improve our mode of living. Properties of elementshelp us determine what it can be used for and what can it be applied to. we refer to these as technology. some of the elements, their properties and uses are shown below:

a.) Hydrogen is the lightest element and is sometimes used to fly balloons. It is also a good fuel

for oxyhydrogen torch. its greatest use is in making ammonia.

b.) Nitrogen is an unreactive gas and abundant in the atmosphere. It is used with argon for

filling electric lamps.Large amount of nitrogen in the air is used in making ammonia, nitric

acid and other nitrogen compounds.

c.) Carbon in activated charcoal has an absorbent property of attracting and holding materials to

its surface. This makes it a good purifier to remove color and odorfrom certain gases and

liquids. It is also used in gas mask to inhale air that is free from air pollution.

d.) Iron, because of its metallic property, is widely used in industry, buildings, motor vehicles,

machines, tools, weapons, ships and many other things.

e.) Copper has a very good conductivity property. It is, therefore, widely used as electric

wirings.

f.) Oxygen supports combustions and it is used in torches for welding.