Assigning numbers to the masses of chemical elements allowed chemistry to develop into a physical science and allowed for relationships between products and reactants

One mole of a substance contains 6.02x 10^23 particles

This number is Avogadro’s constant

The Mole

How many molecules are there in 2g of hydrogen ?

8g of oxygen ? Atoms in 36g of carbon ? What is the mass of 4 mol. of hydrogen

atoms? 1 mol. of methane molecules ?

Questions

How many atoms are there in 30.97g of phosphorus ?

What is the mass (to 2 dec. places) of 1 mol. of magnesium hydroxide ?

What is the mass of 0.0100 mol. of caffeine, C8H902N4 ?

How many moles of ammonia are there in 28.08g

Questions