molecular mass - the total mass of all the atoms in a molecule. The mass of
each atom is simply its total number of protons and neutrons in the atom. Thus, the molecular
mass of a molecule is the total number of protons and neutrons in all the atoms in that
molecule. Obviously, the more atoms there are in a molecule, the higher its molecular mass
will be.
A water molecule has a molecular mass of 18. A sugar (sucrose) molecule has a molecular
mass of 342. Macromolecules have molecular masses in the
thousands or even millions. A good sample of nylon normally has an average molecular mass of
around 18,000.