1.27 What is a mole?
Students should:
1.27 know that the mole (mol) is the unit for the amount of a substance
1.28 understand how to carry out calculations involving amount of substance, relative atomic mass (Ar) and relative formula mass (Mr)
A mole (mol) is the quantity of anything that has the same number of particles as there are atoms found in 12.0 grams of carbon-12.
This number of particles is a very large number : 6 x 1023
One mole of atoms of an element is the amount of that element equal to the relative atomic mass in g.
In other words - one mole of oxygen atoms has a mass of 16g, one mole of Lithium atoms has a mass of 6.9g etc.
Thus there are the same number of atoms in 16g of oxygen as there are atoms in 6.9g Lithium and of course 12g of Carbon.