Carbon 14 is continually being created in the Earth's atmosphere by the interaction of nitrogen and gamma rays from outer space.
Since atmospheric carbon 14 arises at about the same rate that the atom decays, the Earth's levels of carbon 14 have remained constant.
Although it does occur naturally, most commercial graphite is produced by treating petroleum coke, a black tar residue remaining after the refinement of crude oil, in an oxygen-free oven.This lesson is the third in a three-part series about the nucleus, isotopes, and radioactive decay.The first lesson, Isotopes of Pennies, deals with isotopes and atomic mass.So by measuring carbon 14 levels in an organism that died long ago, researchers can figure out when it died.The procedure of radiocarbon dating can be used for remains that are up to 50,000 years old.Back in the 1940s, the American chemist Willard Libby used this fact to determine the ages of organisms long dead.Most carbon atoms have six protons and six neutrons in their nuclei and are called carbon 12. But a tiny percentage of carbon is made of carbon 14, or radiocarbon, which has six protons and eight neutrons and is not stable: half of any sample of it decays into other atoms after 5,700 years.Symbol: C; atomic no: 6; atomic wt: 12.011; valency: 2, 3, or 4; relative density: 1.8–2.1 (amorphous), 1.9–2.3 (graphite), 3.15–3.53 (diamond); sublimes at 3367±25°C; boiling pt: 4827°C 1. Symbol C A naturally abundant, nonmetallic element that occurs in all organic compounds and can be found in all living things. Proteins, sugars, fats, and even DNA all contain many carbon atoms.a nonmetallic element found combined with other elements in all organic matter and in a pure state as diamond and graphite. Diamonds and graphite are pure forms, and carbon is a major part of coal, petroleum, and natural gas. The element carbon is also important, however, outside the chemistry of living things. Symbol C An abundant nonmetallic element that occurs in many inorganic and in all organic compounds, exists freely in amorphous, graphite, and diamond forms and as a constituent of coal, limestone, and petroleum, and is capable of chemical self-bonding to form an enormous number of chemically, biologically, and commercially important molecules.Other significant allotropes include fullerenes and nanotubes.In living organisms, which are always taking in carbon, the levels of carbon 14 likewise stay constant.But in a dead organism, no new carbon is coming in, and its carbon 14 gradually begins to decay.The second lesson, Radioactive Decay: A Sweet Simulation of Half-life, introduces the idea of half-life.