Carbon

Carbon is sometimes called the “king of elements,” and for good reason: it’s everywhere you look! The element has been known to humans since prehistory, when it was found in the form of soot and charcoal. In fact, the word “carbon” comes from the Latin word carbo, which means “charcoal.”

In the fourth century BCE, diamonds—another form of carbon—began to be mined in India. But it would be a long time before anyone figured out that charcoal and diamond were different forms of the same element. In 1694, Italian scientists Gisueppe Averani and Cipriani Targioni took a step toward this discovery when they showed that it is possible to destroy diamonds with heat. They used a kind of magnifying glass to focus the sun’s rays until the diamond burned up!

Then, in 1772, French chemist Antoine Lavoisier showed that when charcoal and diamond were burned, they released the same amount of carbon dioxide. This finding indicated that charcoal and diamonds might be made of the same element—something that was confirmed by British chemist Smithson Tennant in 1796.

In 1954, a team of scientists at General Electric made the first artificial diamond. This process, which was initially expensive, has since become substantially cheaper. Today, synthetic diamonds can cost 75 percent less than natural diamonds, and something like 30 percent of diamonds sold in the United States are synthetic. Artificial diamonds are used in everything from jewelry to power tools and computers.

Carbon is a study in contrasts. Diamond is the hardest naturally occurring substance known to science, but other forms of carbon, like charcoal and graphite, are quite soft. While diamonds conduct electricity poorly, graphite conducts electricity and heat well. Diamond is transparent, which is why it’s desirable as jewelry, while graphite is opaque.

Carbon and carbon compounds have too many uses to count! Hydrocarbons—compounds of hydrogen and carbon—can be used to as fuels or to make plastics. Coal, oil, and natural gas power everything from power plants to automobiles and industrial manufacturing.

In its elemental form, carbon can be alloyed with iron to make metals like carbon steel. Graphite is used in pencils, in glass manufacturing, in batteries, and as a pigment, among other things. Charcoal makes both iron production and weekend barbecues possible!

Carbon can also be made into carbon fiber, which is a strong but lightweight material that’s used in everything from running shoes to bicycles and aircraft. Carbon nanotubes are a part of the fullerene family of molecules, which were first discovered in 1985. These molecules have enormous potential for use in medicine, pharmaceuticals, and electronics.

Among all the elements, carbon forms an incomparable number of compounds. Scientists have characterized more than one million carbon compounds, and new ones are discovered all the time.

In 1828, German chemist Friedrich Wöhler discovered that the biological compound urea could be produced from nonbiological chemicals, uniting the fields of organic chemistry, which focuses on carbon and carbon compounds, and inorganic chemistry, which deals with non-carbon compounds.

Hydrocarbons, which are used in fuels, plastics, and pharmaceuticals, are a common type of carbon compound. However, hydrocarbon fuels have a downside: when burned, they produce carbon dioxide, which when expelled into the atmosphere heightens greenhouse effects, a natural process through which heat is trapped near the Earth’s surface.

Other carbon compounds include alloys such as steel, the carbohydrates consumed by plants and animals, and minerals like marble and limestone. The carbon cycle is the process by which carbon moves between living things and throughout the environment—a complex exchange that makes life on Earth possible.

A whole branch of chemistry (organic chemistry) is devoted to studying carbon. Organic chemistry evolved significantly after 1985, when buckminsterfullerine—an allotrope, or form, of carbon with a soccer ball-shape—was discovered. However, the three best-known carbon allotropes are amorphous carbon (which occurs in nature without a crystalline structure), graphite, and diamond.

In nature, you’ll find carbon in two stable (non-radioactive) isotopes: carbon-12 and carbon-13. Almost 99 percent of naturally occurring carbon is in the form of carbon-12. Carbon-14 is a naturally occurring radioisotope with a half-life of only 5,730 years. That half-life is right in the goldilocks zone for radiocarbon dating—not too short (or it would all be gone) and not too long (or it wouldn’t change enough to show aging)—making it ideal for figuring out the age of ancient artifacts.

In total, there are 15 known carbon isotopes. Carbon-8 is the shortest lived, with a half-life of much less than one second.

Carbon can be found naturally in a variety of compounds and forms. The most common are graphite—whose top three producers in 2023 were China, Madagascar, and Mozambique—anthracite, a type of coal mined in China, Russia, and Ukraine; and diamond, which commonly comes from Russia, Botswana, and the Democratic Republic of the Congo.