Question

Are atomic mass, formula mass and molar mass the same thing?

Answer 1

Atomic mass is the average atomic mass of an element.
Formula mass is total mass of the molecule.
Molar mass is the same as the formula mass.

Explanation:

Atomic mass is the average atomic mass of an element. Many elements are composed of isotopes, atoms with same number of protons, but different numbers of neutrons, thus the mass of the element will change. Different percentages of isotopes for an element, weight the mass, thus an average atomic mass.
Carbon= C Atom
Examples of isotopes: C-12, C-13, C-14

Formula mass is the total mass of a molecule.
H2O=
= (2atoms of hydrogen)(1g/1mole)
+ (1 atom of oxygen)(16g/1mole)= 18 g/mole oxygen.

Formula mass is the same as molar mass.