Since ancient times, Carbon has been known in the form of soot, charcoal, graphite and diamonds. However, the element was named by a French scientist Antonie Lavoisier as he carried out a variety of experiments to reveal its nature. In 1772, he pooled the resources to buy a diamond, which he placed in a closed glass jar. As he and the other chemists focused the sun’s rays on the diamond with a magnifying glass, the diamond burned and disappeared. It was noted that the overall weight of the jar remained unchanged and as it burned, it combined with the oxygen to form carbon dioxide. A similar experiment was conducted by a Swedish scientist Carl Scheele in 1779, which showed that graphite burned to form carbon dioxide and hence, it must be another form of carbon. In 1796, it was established by an English chemist Smithson Tennant that diamond was pure carbon and not its compound. Later in 1855, another English chemist Benjamin Brodie produced pure graphite from carbon, proving graphite as a form of carbon.
The important characteristics of Carbon are:
- Carbon exists within three different dimensional structures in which its allotropes are arranged differently. The common allotropes are graphite, diamond and fullerenes.
- It may also exist in an amorphous state such as glassy carbon, soot or carbon black.
- Of all the elements, Carbon has the highest melting/sublimation point, in the form of a diamond, which is about 350° C and has the highest thermal conductivity of any element.
- Elemental Carbon is an inert substance, which is insoluble in water, diluted acids, bases and organic solvents.
- Carbon binds with oxygen to form carbon monoxide or dioxide at high temperatures.
Generally, Carbon is found in volcanic rock called Kimberlite in South Africa, Arkansas, etc. Another area where diamonds are discovered is the ocean floor of the Cape of Good Hope. Carbon is commonly obtained in coal deposits and is a component of great rock masses made of calcium, magnesium and iron. Dissolved in all natural waters, it is found as carbon dioxide in the atmosphere in combination. The core of the earth contains the largest reservoir of Carbon. Its primary hydrocarbons are coal, petroleum and natural gas.
Carbon has two naturally occurring stable isotopes:
- 13C: It is mainly used in organic chemistry research, for studies into molecular structures, metabolism, food labelling, air pollution and climate change. It also helps to determine the presence of the helicobacter pylori bacteria that causes stomach cancer. It can also be used for the production of the radioisotope N–13.
- 12C: Given the atomic weight of exactly 12.00, it is used as the basis upon which, the atomic weight of other isotopes is determined. Its concentration is further increased in biological materials as the biochemical reactions discriminate against 13C.
Common uses of Carbon include:
- Carbon, mainly in the form of coal, is used as a fuel.
- Its important dimensional structure, Graphite is used for pencil tips, high temperature crucibles, dry cells, electrodes and as a lubricant.
- Diamonds are commonly used in jewellery and because they are so hard, they are used for cutting, drilling, grinding and polishing in industry.
- Carbon black is used as a black pigment in printing ink.
- It forms alloys with iron, out of which, the most common is carbon steel.
- Its isotope 14 C is used to date archaeological events.
- Carbon forms a vast number of compounds with hydrogen, oxygen, nitrogen and other elements and is very important in the areas of chemical industry.
Exposure to carbon black through inhalation may lead to temporary or permanent damage of lungs and heart. Workers engaged in the production of carbon black suffer Pneumoconiosis. Skin exposure to Carbon also leads to skin conditions such as inflammation of the hair follicles and oral mucosal lesions.