the average weight of a molecule of an element or compound measured in units once based on the weight of one hydrogen atom taken as the standard or on 1/16 (0.0625) the weight of an oxygen atom, but after 1961 based on 1/12 (0.083) the weight of the carbon-12 atom; the sum of the atomic weights of all the atoms in a molecule. Abbreviation: mol. wt.
Origin of molecular weight
First recorded in 1875–80
Also called formula weight.
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The sum of the atomic weights of all the atoms in a molecule.formula weight
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The sum of the atomic weights of the atoms contained in a molecule. Also called relative molecular mass
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