The term "molar mass" refers to the mass of one mole of a substance, expressed in grams. It is also known as the molecular weight or formula weight.
The molar mass of an atom, on the other hand, refers to the atomic mass of that atom, expressed in grams. It is the mass of one mole of atoms of a particular element. The molar mass of an atom is numerically equal to its atomic mass in atomic mass units (u) and can be converted to grams by using the conversion factor of 1 gram per mole.
For example, the molar mass of carbon (C) is approximately 12.01 grams per mole (g/mol) because its atomic mass is around 12.01 atomic mass units (u). Similarly, the molar mass of oxygen (O) is approximately 16.00 g/mol due to its atomic mass of about 16.00 u.
Molar mass is essential in various calculations in chemistry, such as determining the mass of a given number of moles of a substance or converting between moles and grams in stoichiometric calculations. It provides a bridge between the atomic scale and macroscopic scale, allowing chemists to quantify substances in a practical and meaningful way.