What is a mole?

A mole is a name given to a certain number of particles. Amounts of various substances are measured in a unit known as the mole (known as mol for short, symbol n). 

One mole is approximate 6.02 x 10²³ particles (this number is known as the Avogadro constant, N_A)

Number of moles  = Number of particles you have ÷ Number of particles in a mole

For example: I have 1.5 x 10²⁴ C atoms - how many moles of carbon do I have? 

Number of moles = (1.5 x 10²⁴) ÷ (6.02 x 10²³)

                            = 2.49 moles