relative formula massTotal mass of the relative atomic masses of all the atoms in a given formula. (Mr) is the sum of the relative atomic mass of all the atoms present in the formula of a substance. Covalent substances are moleculeIs a particle which consists of two or more atoms chemically bonded together.
, so their relative formula massTotal mass of the relative atomic masses of all the atoms in a given formula. is often referred to as relative molecular mass.
Example:
Calcium hydroxide, Ca(OH)2 consists of one calcium atom (Ar = 40), two oxygen atoms (Ar = 16) and two hydrogen atoms (Ar = 1).
