1) Gram Atomic Mass:
The atomic mass of an element expressed in grams is called gram atomic mass or gram atom. It is also called a mole.
1 gram atom of hydrogen = 1.008 g = 1 mol of hydrogen
1 gram atom of carbon = 12.0 g = 1mol of carbon
It means that 1 gram atom of different elements has different masses.
2) Gram Molecular Mass
The molecular mass of an element or a compound expressed in grams is called gram molecular mass or gram molecule. It is also called a mole.
1 gram molecule of H2 = 2.0 g = 1 mol of hydrogen
1 gram molecule of H2O = 18.0 g = 1 mol of water
1 gram molecule of H2SO4 =98.0 g = 1 mol of sulphuric acid
3) Gram Formula Mass
The formula mass of an ionic compound expressed in grams is called gram formula mass or gram formula. This is also called a mole.. For example:
1 gram formula of NaCI = 58.5 g = 1 mol of sodium chloride
1 gram formula of CaCO3 = 100 g = 1 mol of calcium carbonate