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.For any element, one of the isotopes is more abundant in nature than any of the others, although often multiple isotopes of a single element are mixed.The isotope of an element is defined by the nucleon number, which is the sum of the number of protons and the number of neutrons in the atomic nucleus.
The isotope carbon-12 has been adopted as the standard for atomic wt; carbon-14, a radioisotope with a half-life of 5700 years, is used in radiocarbon dating and as a tracer. gr.: (of diamond) 3.51 at 20°C; (of graphite) 2.26 at 20°C.These are the most common naturally occurring isotopes of oxygen and carbon, respectively. An atom of carbon-14 contains 6 protons and 8 neutrons and is denoted Certain isotopes of elements are unstable, giving off ionizing radiation, also known as radioactivity. Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. 1979, 1986 © Harper Collins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Cite This Source radiocarbon dating A technique for measuring the age of organic remains based on the rate of decay of carbon 14. Isotopes of a given element carry different numbers of neutrons, or neutrally charged particles, in their nuclei.The sum of the number of neutrons and protons in an atom's nucleaus defines its approximate atomic weight.