Molecular mass is the mass of a single molecule, equal to the sum of the atomic masses of all the atoms in the molecule. It is normally expressed in atomic mass units. For example, the molecular mass of water is found by adding the atomic masses of two hydrogen atoms and one oxygen atom.

分子质量是单个分子的质量,等于分子中所有原子的原子质量之和。它一般以原子质量单位表示。例如,水的分子质量由两个氢原子和一个氧原子的原子质量相加求得。