Chapter 3 Molecules, Ions, and their Compounds

1
Chapter 3Molecules, Ions, and their Compounds

• Molecular Compounds
• Ionic Compounds
• Nomenclature
• Compounds and Molar Mass
• Percent Composition and Empirical Formulas

2
I. Molecular Compounds

• molecule combination of atoms bounded together
  so strongly that they behave as a single particle
• Ways of representing molecules
• molecular formulas describe composition
• condensed formulas more detail on arrangement
  of atoms
• structural formulas adds bonding info

3

• ball and stick models shows 3-D structure

• space-filling models better representation of
  size

4

• Ethanol

• Dimethyl Ether

5
II. Ionic Compounds

• combinations of at least one metal with one or
  more non-metals
• composed of positive ions (cations) and negative
  ions (anions) joined together in a neutral (no
  charge) crystal
• VERY strong forces between particles
  (electrostatic)

6

• DO NOT exist as single molecules

• DO exist as extended 3-D crystals

• hard, brittle, high-melting solids

7
(No Transcript)
8
Handout -

• Li I
• Al Cl
• Mg S
• Ca N

• Ca Cl
• Rb S
• Li N

Polyatomic Ion - Group of atoms with a net
charge that behaves as a single ionic particle
(Table 3.1 KNOW!!)
9
(No Transcript)
10
Handout -

• magnesium nitrate
• lithium phosphate
• barium cyanide
• ammonium sulfate
• strontium nitrate
• sodium dihydrogen phosphate
• potassium perchlorate
• lithium hydrogen sulfate

11
What determines the strength of an ionic bond?

• charges on the ions (n and n-)
• distance between the ions (d)
• strongest ionic bonds are between small ions with
  high charges

12
III. Nomenclature (Naming)

• Different rules for ionic and molecular compounds
• Use flowchart

13
IV. Compounds and Molar Mass

• Formula mass (molecular mass, molecular weight)
  sum of the atomic masses of all the atoms in the
  formula of a compound
• In an element
• molar mass atomic mass in grams
• In a compound
• molar mass formula mass in grams

14
One-mole quantities of some compounds
15
IV. Percent Composition and Empirical Formulas

• Percent Composition
• percentage of each element (by mass) in a
  compound
• Empirical Formula
• simplest ratio of atoms or ions in a compound
• Identifying an Unknown Compound (Chemical
  Analysis)