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  2. Carbon-12 - Wikipedia

    en.wikipedia.org/wiki/Carbon-12

    Carbon-12 is of particular importance in its use as the standard from which atomic masses of all nuclides are measured, thus, its atomic mass is exactly 12 daltons by definition. Carbon-12 is composed of 6 protons , 6 neutrons , and 6 electrons .

  3. Mass number - Wikipedia

    en.wikipedia.org/wiki/Mass_number

    For example, the most common isotope of carbon is carbon-12, or 12 C, which has 6 protons and 6 neutrons. The full isotope symbol would also have the atomic number (Z) as a subscript to the left of the element symbol directly below the mass number: 12 6 C. [3]

  4. Isotopes of carbon - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_carbon

    Carbon (6 C) has 14 known isotopes, from 8 C to 20 C as well as 22 C, of which 12 C and 13 C are stable.The longest-lived radioisotope is 14 C, with a half-life of 5.70(3) × 10 3 years. . This is also the only carbon radioisotope found in nature, as trace quantities are formed cosmogenically by the reactio

  5. Dalton (unit) - Wikipedia

    en.wikipedia.org/wiki/Dalton_(unit)

    The dalton or unified atomic mass unit (symbols: Da or u, respectively) is a unit of mass defined as ⁠ 1 / 12 ⁠ of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. [1] [2] It is a non-SI unit accepted for use with SI.

  6. Atomic mass - Wikipedia

    en.wikipedia.org/wiki/Atomic_mass

    For comparison, the atomic mass of a carbon-12 atom is exactly 12 daltons. Alternately, the atomic mass of a carbon-12 atom may be expressed in any other mass units: for example, the atomic mass of a carbon-12 atom is 1.992 646 882 70 (62) × 10 −26 kg. As is the case for the related atomic mass when expressed in daltons, the relative ...

  7. Carbon - Wikipedia

    en.wikipedia.org/wiki/Carbon

    Carbon (from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. [13] Carbon makes up about 0.025 percent of Earth's ...

  8. Table of nuclides - Wikipedia

    en.wikipedia.org/wiki/Table_of_nuclides

    A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.

  9. Chemical element - Wikipedia

    en.wikipedia.org/wiki/Chemical_element

    All carbon atoms have 6 protons, but they can have either 6, 7, or 8 neutrons. Since the mass numbers of these are 12, 13 and 14 respectively, said three isotopes are known as carbon-12, carbon-13, and carbon-14 (12 C, 13 C, and 14 C). Natural carbon is a mixture of 12 C (about 98.9%), 13 C (about 1.1%) and about 1 atom per trillion of 14 C.