Trees are Made of Air

By blending water and minerals from below with sunlight and CO2 from above, green plants link the earth to the sky. We tend to believe that plants grow out of the soil, but in fact most of their substance comes from the air. The bulk of the cellulose and the other organic compounds produced through photosynthesis consists of heavy carbon and oxygen atoms, which plants take directly from the air in the form of CO2. Thus the weight of a wooden log comes almost entirely from the air. When we bur...

 Humphry Davy Proves Diamonds are Made of Carbon

In Florence, while the guest of the Grand Duke, Davy performed an impressive carbon-based experiment which proved that the most apparently precious of objects — the diamond — could also be the product of nature’s simplest processes. With the Duke’s permission, he commandeered the huge solar magnifying lens at the Florentine Cabinet of Natural History, and subjected an uncut diamond to intense and continuous heat. The diamond eventually burst into flame, leaving a fine crust of black c...

 Explanation of Isotopes

The number of neutrons in an atom's nucleus is less fixed than the number of protons: many elements have different versions, called isotopes, with different numbers of neutrons. For example, there are three isotopes of carbon, called Carbon-12, Carbon-13 and Carbon-14. The numbers refer to the mass of the atom, which is the sum of the protons and neutrons. Each of the three has six protons. Carbon-12 has six neutrons. Carbon-13 has seven neutrons and Carbon-14 has eight neutrons. Some isotope...

 The Creation of Carbon in Stars

The first step occurs when older stars start to accumulate helium, which is produced when two hydrogen nuclei collide and fuse with each other. This fusion is how stars create the energy that warms us. Two helium atoms can in turn collide to form beryllium, an atom whose nucleus contains four protons. Once beryllium is formed, it could in principle fuse with a third helium nucleus to form carbon. But that doesn't happen, because the isotope of beryllium that is formed decays almost immediatel...

 Carbon Dating

Of all the elements, carbon is the one that seems most indispensable to life - the one without which life on any planet is hardest to envisage. This is because of carbon's remarkable capacity for forming chains and rings and other complex molecular architectures. It enters the food web via photosynthesis, which is the process whereby green plants take in carbon dioxide molecules from the atmosphere and use energy from sunlight to combine the carbon atoms with water to make sugars. All the car...