Sponge Give the ionic compound for the following: K+ + O2- Sr2+ + Cl- Na+ + F- Fe3+ + Cl-

Ionic Bonding Part 2 Chemistry Unit 3, Day 2

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

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

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+ = 0 charge, check! Li2O

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

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

Think-Pair-Share: complete the chart by creating the formula unit 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 Li+ Li2S Lithium Sulfide 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+

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!