Science at a Distance

Carbon Atomic Structure

Carbon

Life is based on the chemical and physical properties of the element carbon. It is not a plentiful substance and only makes up about 0.025 percent of the Earth's crust. However, carbon reacts with more other atoms and forms more compounds than all the other elements put together.

Pure carbon can be found in three different forms; diamond, graphite and carbon black. Diamond and graphite are both crystalline but differ the way their atoms are arranged. Diamond is the hardest naturally occurring substance known, while graphite is soft and slippery. Graphite is also a good conductor of both heat and electricity and is used as a lubricant and as the "lead" of pencils. Both diamond and graphite can be made artificially and are usually inert but, under the right circumstances, can be made combine with oxygen. Diamonds do burn.

Carbon black is amorphous. Examples include charcoal, coal, and coke, all of which are the products of oxidation and breakdown of organic compounds. Coal and coke, are used as fuels. Charcoal is used as a filtering agent, a fuel and as part of gunpowder. Carbon black also is added to the rubber in tires where it makes the tires last longer.

Compounds of Carbon

About 0.03 percent (by volume) of the Earth's atmosphere is carbon dioxide and more carbon is found as marble, limestone, chalk, coal, petroleum, and natural gas in the Earth's crust.

Human scientists have recognized or synthesized more than 1,000,000 carbon compounds, and many new ones are added each year to the list. This diversity of organic forms stems from the capacity of carbon atoms to unite not only with other carbon atoms but also with a large variety of other atoms. Carbon compounds and their chemistry are a specialized field of study called organic chemistry, so called because early chemists thought that all carbon compounds originated in living organisms.

Organic carbon compounds make up about 18 percent of all the matter in living things. In these molecules, carbon joins up with hydrogen, nitrogen, oxygen, phosphorous and sulfur to make the large and small building blocks of life.


Science at a Distance
© 2000, Professor John Blamire