Molecular formula shows the number of atoms of each element present in one molecule of a compound.
Relative molecular mass (Mr) = sum of relative atomic masses of atoms present
The relative atomic mass is the weighted average of all naturally occurring isotopes.
Relative Formula Mass (RFM) is calculated by adding up the atomic masses of all elements in the molecular formula, multiplied by their coefficients.
The RFM can be used to calculate the molar mass of a substance from its relative formula mass.
Average Atomic Mass (AM): The average mass of an atom of an element based on the abundance of different isotopes.
The relative molecular mass is calculated by adding up the relative atomic masses of all the elements present in the compound, using their coefficients from the chemical equation.