Question

Define atomic mass along with some examples. How is it different from molecular mass?

Answer 1

Atomic mass is defined as the mass of an atom expressed in atomic mass unit (amu or u). One atomic mass unit (amu) is defined as a mass equal to one-twelfth (1/12th) the mass of one carbon-12 atom.

Examples:

• Atomic mass of hydrogen = 1 u
• Atomic mass of oxygen = 16

Molecular mass is defined as the sum of the atomic masses of all the atoms that constitute a molecule.
Example:
Molecular mass of water = (2 x Atomic mass of H) + (1 x Atomic mass of O)
= 2 u + 16 u = 18 u.