2. Question??? Apples cost $0.50 Pears cost $0.40 You want an apple and have $0.45 Your friend wants a pear and has $0.45 How can you both be happy?

3. Ions and Ionic Bonds Atoms with 5, 6, or 7 valence electron tend to receive electrons Atoms with 1, 2, or 3 valence electron tend to give electrons Transfers make both atoms stable and therefore happy!

4. Ions An Atom or group of Atoms with an electrical charge Remember electrons are negative charges Atom losses electron = positive charge Atom gains electron = negative charge

5. Polyatomic Ions Poly = many Ions made of more then 1 atom Think of it as a group of atoms that act like a single unit Examples: Nitrate NO 3 - Ammonium NH 4 +

6. Lets look at Salt Na gives 1 electron (loses 1) becoming a positive ion Na + Cl gains 1 electron becoming a negative ion Cl - Opposite charges attract forming an ionic bond Pg 23 (table of Ions)

7. Ionic Compound Compound that consists of a positive and negative ion is called an ionic compound Look at the table on page 23, what are some ionic compounds, write down 5

8. Chemical formulas Chemical formula: Symbol the shows the ratio of elements in a compound Magnesium Chloride = MgCl 2 1 Mg is bonded with 2 Cl Mg 2+ (+2) Cl - (-1) To balance the charge you need 2 Cl for every 1 Mg

9. Naming Ionic Compounds Positive ion first Negative ion second Positive ion is usually a metal

10. More on Naming Negative single element ion ide Negative polyatomic ion ite, ate

11. Properties of Ionic Bonds Hard, brittle crystals High melting points Conduct electricity when dissolved in water or melted

12. Ionic Crystals Ions form orderly 3d arrangements we call crystals Same pattern no matter how large

13. Melting Point High Melting points Increasing energy will break bonds When bonds break crystal is broken and it will melt Ionic bonds need a lot of energy to break

14. Electrical Conductivity Flow of charged partials = electrical current Dissolving ionic compounds break the bonds Ions float around in the water Solid ionic compounds do not let ions move Therefore not very conductive