What is "molecular weight"

Molecular \Mo*lec"u*lar\, a. [Cf. F. mol['e]culare. See Molecule.] (Phys. & Chem.) Pertaining to, connected with, produced by, or consisting of, molecules; as, molecular forces; molecular groups of atoms, etc. Molecular attraction (Phys.), attraction acting between the molecules of bodies, and at insensible distances. Molecular weight (Chem.), the weight of a molecule of any gas or vapor as compared with the hydrogen atom having weight of 1 as a standard; the sum of the atomic weights of the constituents of a molecule; thus, the molecular weight of water ( H2O) is 18. For more precise measurements, the weight of the carbon isotope carbon-12 is used as the standard, that isotope having the value of 12.000. In this systen, now used almost universally, the hydrogen atom has a weight of

1. 0079.

n. (context chemistry English) the sum of the atomic weights of every atom in a molecule

n. (chemistry) the sum of the relative atomic masses of the constituent atoms of a molecule [syn: relative molecular mass]