C3 - Moles

What does the term "mole" mean in chemistry?

A mole represents a very large number of particles (atoms, ions or molecules) called Avogadro's number.

What is Avogadro's number (in words)?

The number of particles in one mole of a substance. (You don't need the exact value yet, it's covered later.)

What is the link between Ar (relative atomic mass) and moles?

The Ar of an element in grams is equal to one mole of atoms of that element.

Example: What is the relative atomic mass (Ar) of carbon?

12

How many grams of carbon equal 1 mole?

12 g of carbon = 1 mole of carbon atoms.

General rule for any element

The relative atomic mass (Ar) in grams = 1 mole of atoms of that element.

Why is the mole useful in chemistry?

It allows scientists to calculate how many atoms of a substance are used in a chemical reaction.

What is the key equation for moles of an element?

Number of moles = Mass (g) ÷ Relative atomic mass (Ar).

Does relative atomic mass (Ar) have units?

No, it has no units.