A mole of a substance or a mole of particles is defined as exactly 6.02214076×10²³ particles, which may be atoms, molecules, ions, or electrons.

The mole is important because it allows chemists to work with the subatomic world with macro world units and amounts.

**Formula to calculate moles.**

Mass of one mole of the substance can be found in a periodic table.

**Example:**

Determine the moles in 20.0 grams of NaCl.

Since we know from the periodic table that the mass of one mole of sodium chloride is 58.44 grams, then;

Therefore, the number of moles in 20.0 grams of sodium chloride is 0.34.