Untitled Essay, Research Paper

I. IntroductionA. The History of Carbon

II. Occurrences in NatureA. DiamondB. GraphiteC. Coal and CharcoalD. Amorphous Carbon

III. Carbon CompoundsA. InorganicB. Organic

IV. The Carbon Cycle

IV. ConclusionCarbon, an element discovered before history itself, is one of the

most abundant elements in the universe. It can be found in the sun, the

stars, comets, and the atmospheres of most planets. There are close to ten

million known carbon compounds, many thousands of which are vital to the

basis of life itself (WWW 1).Carbon occurs in many forms in nature. One of its purest forms is

diamond. Diamond is the hardest substance known on earth. Although

diamonds found in nature are colorless and transparent, when combined with

other elements its color can range from pastels to black. Diamond is a

poor conductor of heat and electricity. Until 1955 the only sources of

diamond were found in deposits of volcanic origin. Since then scientists

have found ways to make diamond from graphite and other synthetic

materials. Diamonds of true gem quality are not made in this way (Beggott

3-4).Graphite is another form of carbon. It occurs as a mineral in

nature, but it can be made artificially from amorphous carbon. One of the

main uses for graphite is for its lubricating qualities. Another is for

the "lead" in pencils. Graphite is used as a heat resistant material and

an electricity conductor. It is also used in nuclear reactors as a

lubricator (Kinoshita 119-127).Amorphous carbon is a deep black powder that occurs in nature as a

component of coal. It may be obtained artificially from almost any organic

substance by heating the substance to very high temperatures without air.

Using this method, coke is produced from coal, and charcoal is produced

from wood. Amorphous carbon is the most reactive form of carbon. Because

amorphous carbon burns easily in air, it is used as a combustion fuel. The

most important uses for amorphous carbon are as a filler for rubber and as

a black pigment in paint (WWW 2).There are two kinds of carbon compounds. The first is inorganic.

Inorganic compounds are binary compounds of carbon with metals or metal

carbides. They have properties ranging from reactive and saltlike; found

in metals such as sodium, magnesium, and aluminum, to an unreactive and

metallic, such as titanium and niobium (Beggott 4).Carbon compounds containing nonmetals are usually gases or liquids

with low boiling points. Carbon monoxide, a gas, is odorless, colorless,

and tasteless. It forms during the incomplete combustion of carbon

(Kinoshita 215-223). It is highly toxic to animals because it inhibits the

transport of oxygen in the blood by hemoglobin (WWW 2). Carbon dioxide is

a colorless, almost odorless gas that is formed by the combustion of

carbon. It is a product that results from respiration in most living

organisms and is used by plants as a source of carbon. Frozen carbon

dioxide, known as dry ice, is used as a refrigerant. Fluorocarbons, such

as Freon, are used as refrigerants (Kinoshita 225-226).Organic compounds are those compounds that occur in nature. The

simplest organic compounds consist of only carbon and hydrogen, the

hydrocarbons. The state of matter for organic compounds depends on how

many carbons are contained in it. If a compound has up to four carbons it

is a gas, if it has up to 20 carbons it is a liquid, and if it has more

than 20 carbons it is a solid (Kinoshita 230-237).The carbon cycle is the system of biological and chemical processes

that make carbon available to living things for use in tissue building and

energy release (Kinoshita 242). All living cells are composed of proteins

consisting of carbon, hydrogen, oxygen, and nitrogen in various

combinations, and each living organism puts these elements together

according to its own genetic code. To do this the organism must have these

available in special compounds built around carbon. These special

compounds are produced only by plants, by the process of photosynthesis.

Photosynthesis is a process in which chlorophyll traps and uses energy from

the sun in the form of light. Six molecules of carbon dioxide combine with

six molecules of water to form one molecule of glucose (sugar). The

glucose molecule consists of six atoms of carbon, twelve of hydrogen, and

six of oxygen. Six oxygen molecules, consisting of two oxygen atoms each,

are also produced and are discharged into the atmosphere unless the plant

needs energy to live. In that case, the oxygen combines with the glucose

immediately, releasing six molecules of carbon dioxide and six of water for

each molecule of glucose (Beggott 25-32). The carbon cycle is then

completed as the plant obtains the energy that was stored by the glucose.

The length of time required to complete the cycle varies. In plants

without an immediate need for energy, the chemical processes continue in a

variety of ways. By reducing the hydrogen and oxygen content of most of

the sugar molecules by one water molecule and combining them to form large

molecules, plants produce substances such as starch, inulin , and fats

and store them for future use. Regardless of whether the stored food is

used later by the plant or consumed by some other organism, the molecules

will ultimately be digested and oxidized, and carbon dioxide and water will

be discharged. Other molecules of sugar undergo a series of chemical

changes and are finally combined with nitrogen compounds to form protein

substances, which are then used to build tissues (WWW 2).Although protein substances may pass from organism to organism,

eventually these too are oxidized and form carbon dioxide and water as

cells wear out and are broken down, or as the organisms die. In either

case, a new set of organisms, ranging from fungi to the large scavengers,

use the waste products or tissues for food, digesting and oxidizing the

substances for energy release (WWW 1).

At various times in the Earth’s history, some plant and animal

tissues have been protected by erosion and sedimentation from the natural

agents of decomposition and converted into substances such as peat,

lignite, petroleum, and coal. The carbon cycle, temporarily interrupted in

this manner, is completed as fuels are burned, and carbon dioxide and water

are again added to the atmosphere for reuse by living things, and the solar

energy stored by photosynthesis ages ago is released (Kinoshita 273-275).Almost everything around us today has some connection with carbon

or a carbon compound. Carbon is in every living organism. Without carbon

life would not exist as we know it.

Works Cited1. Beggott, Jim Great Balls of Carbon New Scientist,

July 6, 19912. Kinoshita, Kim Carbon Compounds Random, New York 119-275

19873. WWW Carbon http://ww