1. Properties of Ionic Bonds Unit XX, Presentation 2

2. Properties of Ionic Compounds l They are formed as crystalline structure. –A regular repeating arrangement of ions in the solid. –Ions are strongly bonded (electrostatic attraction) –Crystal structure is very rigid l Ionic compounds have high melting points – because of strong forces between ions.

3. Crystalline structure

4. Do they Conduct? l Conducting electricity means charges are allowed to move. l In a solid, the ions are locked in place –No charges can move l Ionic solids are excellent insulators

5. Do they Conduct? l Melting the compounds allows the ions to move freely. l When melted the ions are no longer locked in place –Separate ions can move –Moving ions can conduct electricity l Molten ionic compounds conduct electricity –First get them to around 800ºC –Then the ions have freedom of movement

6. Do they Conduct? l When dissolved water allows the ions to separate –Separate ions can move –Moving ions can conduct electricity

7. Metallic Bonds l How electrons are held together in the metallic solid –Metals hold onto their valence electrons very loosely Due to a small electronegativity –Electrons are not held in the valance shell l Think of metals as positive ions floating in a sea of electrons

8. Sea of Electrons l Electrons are free to move through the solid l Can metals conduct electricity?

9. Metals are Malleable l Hammered into shape (bend). l Ductile - drawn into wires.

10. Malleable ++++ ++++ ++++

11. ++++ ++++ ++++ l Electron cloud allows ions to slide by

12. Ionic solids are brittle +-+- + - +- +-+- + - +-

13. + - + - + - +- +-+- + - +- l Strong Repulsion breaks crystal apart.