Sponge

1
Sponge

• Give the ionic compound for the following
• K O2-
• Sr2 Cl-
• Na F-
• Fe3 Cl-

2
Ionic Bonding Part 2

• Chemistry
• Unit 3, Day 2

3
Properties of Ionic Compounds

• Crystal Lattice Structure
• Each positive ion is surrounded by negatives
• Each negative ion is surrounded by positives
• Strong Bonds
• Require large amounts of energy to break apart
• High melting points
• High boiling points
• Hard, Rigid, Brittle solids

4
Strength of the Bond

• Energy required to separate one mole of the ions
  of an ionic compound is referred to as Lattice
  Energy
• The more negative the energy, the stronger the
  force of attraction, the harder to separate ions

Compound Lattice Energy (kJ/mol)
KBr -671
NaBr -732
AgCl -910
SrCl2 -2142
5
RECALL Writing Formula Units

• The formula unit (product) must be neutral (zero
  charge)
• Add the ions involved
• The cation is written first, then the anion

• Li and O2-
• 1
• -2
• -1 charge, need
• Li O2- Li
• 1
• -2
• 1
• 0 charge, check!
• Li2O

6
Oxidation Numbers

• The charge on the ion is called its oxidation
  number or oxidation state
• Atoms can have more than one oxidation number

7
Naming Monatomic Ionic Compounds

• Monatomic- an ion made up of one type of atom
  (Li, Na, O2-, etc.)
• The cation is given its full name
• The anion uses the suffix ide
• For example, Li and O2-
• Lithium Oxide
• For example, Na and Cl-
• Sodium Chloride

8
Think-Pair-Share complete the chart by creating
the formula unit. Leave room to also include the
name of the compound.
F- O2- N3- S2-
Na 1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
Na2O Sodium Oxide
Na2S Sodium Sulfide
NaF Sodium Fluoride
Na3N Sodium Nitride
LiF Lithium Fluoride
Li2O Lithium Oxide
Li3N Lithium Nitride
Li2S Lithium Sulfide
Li
MgF2 Magnesium Fluoride
MgO Magnesium Oxide
Mg3N2 Magnesium Nitride
MgS Magnesium Sulfide
Mg2
BeF2 Beryllium Fluoride
BeO Beryllium Oxide
Be3N2 Beryllium Nitride
BeS Beryllium Sulfide
Be2
9
Guided Practice reading charts
Compound Lattice Energy (kJ/mol) Melting Point (C)
KI -632 681
KF -808 858

• Which is a stronger bond? Why?
• KF, more negative energy
• Which has a higher melting point?
• KF
• What is the relationship between ionic bond
  strength and melting point?
• The stronger the bond, the higher the melting
  point!