Define what 1 mole is

1 mole is just a unit of the amount of particles present in a substance. Here are several definition that all interlink: Mathematically speaking, 1 mole = mass of substance / Molecular Formula Mass. For it to be 1 mole, the mass has to be the same as the Molecular Formula. So, in 23 grams of sodium, there are 1 moles, because the Mr of sodium is 23. A question to think about: are there 16g or 32g in 1 mole of Oxygen?