| 单词 | relative molecular mass |
| 释义 | > as lemmasrelative molecular mass relative molecular mass n. Physical Chemistry the average mass of the molecules of a substance expressed by comparison to a standard atom (formerly one of hydrogen or oxygen, now one of the isotope carbon-12) and equivalent to the sum of the relative atomic masses of the constituent atoms; also called molecular weight. ΚΠ 1866 J. Bayma Elements Molecular Mech. xii. 251 Chemical equivalents, as we have above observed, do not express absolute, but only relative molecular masses. Thus for hydrogen and oxygen we have the proportion H : O :: 1 : 16. 1891 Jrnl. Amer. Chem. Soc. 13 18 The number expressing the relative molecular mass of an element, represents in milligrammes the absolute mass of a quadrillion atoms of that element. 1964 H. S. Hvistendahl Engin. Units iv. 52 The International Unions of Pure and Applied Physics and of Pure and Applied Chemistry have now agreed that both scales be replaced by one based on an atomic mass unit (amu) equal to 1/12th of the mass of the neutral carbon atom... It is also recommended that the misnomers ‘atomic weight’ and ‘molecular weight’, be renamed relative atomic mass and relative molecular mass, respectively. 1995 New Scientist 11 Nov. 18/1 The finished structure..contains more than 700 atoms in total and has a relative molecular mass of about 24 000. < as lemmas |
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