What is the molecular weight of a molecule?

1. The molecular weight of the molecule is defined as the sum of each constituent element present in it.
2. In simple words we can say that it is the overall or the total mass of the molecules constituting the individual unit.
3. The unit is $gmo{l}^{-1}$.
4. Example: Molecular weight of water molecule${\mathrm{H}}_2\mathrm{O}$.
5. The atomic mass of Hydrogen is $1.$
6. As two Hydrogen is present then the atomic weight becomes two times the atomic weight $2.$
7. The atomic mass of oxygen is $16$.
8. Thus the molecular weight of water is $16+2=18{\mathrm{gmol}}^{-1}$