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Isotopomers or isotopic isomers are isomers with isotopic atoms, having the same number of each isotope of each element but differing in their positions in the molecule. The result is that the molecules are either constitutional isomers or stereoisomers solely based on isotopic location.
In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element – but distinct arrangements of atoms in space. [1] Isomerism refers to the existence or possibility of isomers. Isomers do not necessarily share similar chemical or physical properties.
A nuclide is a species of an atom with a specific number of protons and neutrons in the nucleus, for example, carbon-13 with 6 protons and 7 neutrons. The nuclide concept (referring to individual nuclear species) emphasizes nuclear properties over chemical properties, whereas the isotope concept (grouping all atoms of each element) emphasizes chemical over nuclear.
Hydrogen (1 H) has three naturally occurring isotopes: 1 H, 2 H, and 3 H. 1 H and 2 H are stable, while 3 H has a half-life of 12.32(2) years. [3] [nb 1] Heavier isotopes also exist; all are synthetic and have a half-life of less than 1 zeptosecond (10 −21 s). [4] [5] Of these, 5 H is the least stable, while 7 H is the most.
In chemistry, isotopologues (also spelled isotopologs) are molecules that differ only in their isotopic composition. [1] They have the same chemical formula and bonding arrangement of atoms, but at least one atom has a different number of neutrons than the parent.
Archaeological materials, such as bone, organic residues, hair, or sea shells, can serve as substrates for isotopic analysis. Carbon, nitrogen and zinc isotope ratios are used to investigate the diets of past people; these isotopic systems can be used with others, such as strontium or oxygen, to answer questions about population movements and cultural interactions, such as trade.
^ Tantalum-180m is a "metastable isotope", meaning it is an excited nuclear isomer of tantalum-180. See isotopes of tantalum . However, the half-life of this nuclear isomer is so long that it has never been observed to decay, and it thus is an "observationally stable" primordial nuclide , a rare isotope of tantalum.
Most of the isotopes with atomic mass numbers below 14 decay to isotopes of carbon, while most of the isotopes with masses above 15 decay to isotopes of oxygen. The shortest-lived known isotope is nitrogen-10, with a half-life of 143(36) yoctoseconds, though the half-life of nitrogen-9 has not been measured exactly.