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Enantiotopic groups are identical and indistinguishable except in chiral environments. For instance, the CH 2 hydrogens in ethanol (CH 3 CH 2 OH) are normally enantiotopic, but can be made different (diastereotopic) if combined with a chiral center, for instance by conversion to an ester of a chiral carboxylic acid such as lactic acid, or if coordinated to a chiral metal center, or if ...
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 reaction 14 N + n → 14 C + 1 H. The most ...
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.
The boiling points of the carbon group tend to get lower with the heavier elements. At standard pressure, carbon, the lightest carbon group element, sublimes at 3825 °C. Silicon's boiling point is 3265 °C, germanium's is 2833 °C, tin's is 2602 °C, and lead's is 1749 °C. Flerovium is predicted to boil at −60 °C. [11] [12] The melting ...
The darker more stable isotope region departs from the line of protons (Z) = neutrons (N), as the element number Z becomes larger. This is a list of chemical elements by the stability of their isotopes. Of the first 82 elements in the periodic table, 80 have isotopes considered to be stable. [1] Overall, there are 251 known stable isotopes in ...
They include the biologically most essential elements besides hydrogen: carbon, nitrogen, and oxygen. Lithium (Li) is the lightest metal and the least dense solid element. [ 8 ] In its non-ionized state it is one of the most reactive elements, and so is only ever found naturally in compounds .
New ingredients in the spotlight “Turnips are about to have a moment. A humble root vegetable that is going to get shown some more widespread love.” —Jake Potashnick, executive chef/owner of ...
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.