The following relationships are used to relate number of things to moles and mass.


Relationship between number of things, N, and number of moles, n.

N  = NA n               where: NA = 6.022 x 1023 mol-1


Relationship between moles and mass

where
M   is the molar mass (from the periodic chart) with units of g mol-1
m   is the mass in g
 n   is the number of moles  

The molar mass is read off the periodic chart.  If the species is a molecule (or formula unit), the molar mass is the sum of the molar masses of the atoms in the molecule (or formula unit).