a chemical element, atomic number 6, atomic weight 12.011. (See Appendix 6.) carbon 11a radioactive isotope of carbon, atomic mass 11, having a half-life of 20.39 minutes; used as atracerinpositron emissiontomography. carbon 14a radioactive isotope of carbon, atomic mass 14, having a half...
Isotopesrefer to any of the two or more forms of the same element. They have the same number of protons but differ in the number of neutrons in their nuclei. Therefore, they differ inatomic mass number. Nevertheless, they display almost identical chemical properties. Carbon isotopes that occur...
Atomic mass unit (amu): A unit used to express the mass of an atom equal to exactly one-twelfth the mass of a carbon-12 atom. Isotopes: Two or more forms of an element with the same atomic number (same number of protons in their nuclei), but different atomic masses (different numbe...
This illustrations shows the atomic structure of Carbon-12, Carbon-13 and Carbon-14. (Image credit: Nandalal Sarkar via Shutterstock) Carbon's discovery is lost to history. The element was known to prehistoric humans in the form of charcoal. Carbon as coal is still a major source of fuel ...
a nonmetallic element existing in the three crystalline forms: graphite, diamond, and buckminsterfullerene: occurring in carbon dioxide, coal, oil, and all organic compounds. The isotopecarbon-12has been adopted as the standard for atomic wt;carbon-14, a radioisotope with a half-life of 5700 yea...
Define carbon-12. carbon-12 synonyms, carbon-12 pronunciation, carbon-12 translation, English dictionary definition of carbon-12. n. A stable isotope of carbon, having six protons and six neutrons in the nucleus. Carbon-12 makes up most naturally occurri
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Carbon is the fourth most abundant chemical element in the universe by mass after hydrogen, helium, and oxygen. Carbon is abundant in the Sun, stars, comets, and in the atmospheres of most planets. Some meteorites contain microscopic diamonds that were formed when the solar system was still a...
Carbon is a Group 14 element and is distributed very widely in nature. It is found in abundance in the sun, stars, comets, and atmospheres of most planets. Carbon is present as carbon dioxide in the atmosphere and dissolved in all natural waters. It is a component of rocks as carbonates...
Carbon is the second mostabundant element in humans, by mass (after oxygen). Approximately 20% of the mass of a living organism is atomic number 6. Carbon is the fourth most abundant element in the universe. The element forms in stars via the triple-alpha process in which helium atoms fus...