The Moleand Avogadro’s Number

• Mole (n): the amount of substance• 6.02x1023 particles (atoms or

molecules) of a substance• The same number of particles as

atoms in 12 grams of carbon-12

mole

particlesx

1

1002.6 23

particlesx

mole231002.6

1

Review

• How many atoms are there in 1.2 moles of oxygen?

• Calculate the number of moles of nitrogen equal to 3.45x1015 atoms of nitrogen.

Counting Atoms

• CO• CO2

• Fe(NO3)3

• C6H12O6

• potassium carbonate

• How many molecules in 5 moles of water?

• How many hydrogen atoms in 5 moles of water?

• How many atoms in 5 moles of water?

1. How many chloride ions are there in zinc chloride?

2. A sample of zinc chloride contains 3.1x1019 molecules. a. How many moles is this?

b. How many zinc ions?

c. How many chloride ions?

• Stop.

Masses of Compounds

• Atomic mass (A): the mass of an atom of an element relative to (compared to) other elements (g/mol)

• Ionic: formula unit• Molecular (covalent): molecule

• Formula mass: sum of the atomic masses of the atoms in the compound’s formula (IONIC) (g/mol)

• Molecular mass: sum of the atomic masses of all the atoms in one molecule (COVALENT) (g/mol)

• Molar mass (M): the mass of one mole of any substance (g/mol)–atoms, molecules, ions, etc.

IonicFormula

Mass

CovalentMolecular

Mass

MolarMass

Calculating Molar Mass

• Stop.

1. Calculate the mass of 1.98 moles of iron (II) nitrate.

2. How many molecules are there in 1.00 grams of iron (II) nitrate?

3. Calculate the mass of one molecule of iron (II) nitrate.