1. Anything in black letters = write it in your notes (‘knowts’)
Chapter 10
Chemical Quantities
10.1 – Atomic, Molecular, & Formula Masses; Percent Composition.
10.2 – The Mole & Avogadro’s Number
10.3 – Molar Mass & Mole-Mass Conversions
Anything in black letters = write it in your notes (‘knowts’)

2. Atomic Mass - mass of an atom (a.m.u.)
10.1 – Atomic, Molecular, & Formula Masses; Percent Composition.
3 similar but slightly different terms…
Atomic Mass -
mass of an atom (a.m.u.)
1 C atom = a.m.u.
Molecular Mass -
mass of a molecule (a.m.u.)
1 CO2 molecule = (15.999)
= a.m.u.
Formula Mass -
mass of a formula unit (a.m.u.)
1 MgO formula unit =
= a.m.u.

3. Remember…
Ionic compounds are composed of formula units.
Covalent compounds are composes of molecules.

4. Example: calculate the percent composition of oxygen in K2CrO4

5. Example: calculate the percent composition of oxygen in K2Cr2O7

6. ASSIGNMENT:
Chapter 10 Worksheet #1