What is the molar mass of an element?

the total number of particles in one gram of the element

the mass of 6.02 x 1023 representative particles of the element

the number of amus (atomic mass units) in 6.02 x 1023 moles of the element

1.0 gram divided by the atomic weight of the element

The answer is: the mass of 6.02 x 1023 representative particles of the element.

The base SI unit for molar mass is kg/mol, but chemist more use g/mol (gram per mole).

For example, molar mas of ammonia is 17.031 g/mol.

M (NH₃) = Ar (N) + 3 · Ar (H) · g/mol.

M (NH₃) = 14.007 + 3 · 1.008 · g/mol.

M (NH₃) = 17.031 g/mol.

The molar mass (M) is the mass of a given substance (in this example ammonia) divided by the amount of substance.