Search results
Results from the WOW.Com Content Network
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
The number of nucleons (both protons and neutrons) in the nucleus is the atom's mass number, and each isotope of a given element has a different mass number. For example, carbon-12, carbon-13, and carbon-14 are three isotopes of the element carbon with mass numbers 12, 13, and 14, respectively. The atomic number of carbon is 6, which means that ...
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 ...
Of the 26 "monoisotopic" elements that have only a single stable isotope, all but one have an odd atomic number—the single exception being beryllium. In addition, no odd-numbered element has more than two stable isotopes, while every even-numbered element with stable isotopes, except for helium, beryllium, and carbon, has at least three.
For 12 C, the isotopic mass is exactly 12, since the atomic mass unit is defined as 1/12 of the mass of 12 C. For other isotopes, the isotopic mass is usually within 0.1 u of the mass number. For example, 35 Cl (17 protons and 18 neutrons) has a mass number of 35 and an isotopic mass of 34.96885. [7]
For example, the relative isotopic mass of a carbon-12 atom is exactly 12. 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.
However, the relative atomic mass of each isotope is quite close to its mass number (always within 1%). The only isotope whose atomic mass is exactly a natural number is 12 C, which has a mass of 12 Da; because the dalton is defined as 1/12 of the mass of a free neutral carbon-12 atom in the ground state.
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 .