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’)

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 = 12.011 a.m.u. Molecular Mass - mass of a molecule (a.m.u.) 1 CO2 molecule = 12.011 + 2(15.999) = 44.009 a.m.u. Formula Mass - mass of a formula unit (a.m.u.) 1 MgO formula unit = 24.305 + 15.999 = 40.304 a.m.u.

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

Example: calculate the percent composition of oxygen in K2CrO4

Example: calculate the percent composition of oxygen in K2Cr2O7

ASSIGNMENT: Chapter 10 Worksheet #1