⁕ Gram Atomic Mass (g atom)
↪ Atomic mass is simply a number, which does not have any unit of mass.
↪ The atomic mass or simply gram atom is the atomic mass expressed in terms of grams.
↪ Therefore, 1 gram atom of hydrogen weighs 1 gram.
Similarly 1 gram of Oxygen, Sulphur and Sodium weigh 16g, 32g and 23g respectively.
Number of gram atom of element =
Further, gram atom is denoted as mole of atoms.
⁕ Gram Molecular Mass (g mole)
↪ The molecular mass is a relative term and it is a unit less number.
e.g. molecular mass of H2SO4 = 98.
↪ It means, the weight of 1 molecules of H2SO4 is 98 times heavier than the mass of 1/12th of an atom of C-12 isotope (i.e. 1 amu).
↪ When the molecular mass of substance is expressed in gram, it is called one gram molecular mass or 1 g mole.
Molecular mass of H2 = 2 amu and 2 g of H2 = 1 g mole of H2
Molecular mass of CO2 = 44 amu and 44 g of CO2 = 1 g mole of CO2
Mathematically, we have
No. of mole =
Further, g mole is denoted as mole of molecules.