It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms.When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons).Carbon is one of the most important elements to life on planet Earth.It forms more compounds than any other element and forms the basis to all plant and animal life.Carbon-14 is radioactive, with a half-life of about 5,700 years.For more information on cosmic rays and half-life, as well as the process of radioactive decay, see How Nuclear Radiation Works.Isotopes There are two stable naturally occurring isotopes of carbon, carbon-12 and carbon-13.
Animals and people eat plants and take in carbon-14 as well.
Allotropes are materials made from the same element, but their atoms fit together differently.
Each allotrope of carbon has different physical properties.
One of the key characteristics of carbon is its ability to make long chains of molecules through linking up with other carbon atoms. It is a major element in many rock formations such as limestone and marble.
Carbon also has the highest melting point of all the elements. It is found in its allotropic forms of diamond, graphite, and amorphous carbon throughout the world. Carbon is used in some way in most every industry in the world.