1. Ionic Compounds

2. Forming Chemical Bonds Objectives –Define chemical bond –Relate chemical bond formation to electron configuration –Describe the formation of positive and negative ions

3. Chemical Bonds The force that holds two atoms together… –WHY?

4. Electron Dot structure Recall them… –Do some on board Recall “ion” Write electron configurations for potassium and argon –What’s the difference? –Why is argon so stable? –How could potassium achieve stability?

5. Ions How do atoms become ions? Positive ions –They always want to achieve the most stable state…8 valence electrons –Look at Ne and Na’s configurations –Ionization energy is key…

6. Negative Ions Look at argon and chlorine –Anions gain electrons in bonding to achieve noble gas configuration

7. Homework 8.1 assessment P.236 # 47-50; 60-66

8. Formation of Ionic Bond Objectives –Describe the formation of ionic bonds –Account for many of the physical properties of an ionic compound –Discuss the energy involved in the formation of an ionic bond

9. Ionic Bonding Atoms transfer electrons from one to another forming a bond between two ions. The electrostatic force that holds oppositely charged particles together in an ionic compound is referred to as an ionic bond Ionic bonds are extremely strong bonds

11. Ionic Bonds Binary compounds –Contains two different elements –Ex: MgO Is CaSO 4 a binary compound? Polyatomic ion: an ion that contains more than one element –SO4 - –OH -

12. Properties of Ionic Compounds Ions packed into regular repeating patterns called crystals (crystal lattice)

13. Crystals High-energy bonds Melting point, boiling point and hardness all depend on strength of bond –Stronger = higher boiling and melting pts.

14. Properties High melting and boiling points - Ionic bonds are very strong - a lot of energy is needed to break them.... Conductive when aqueous - Ions are charged particles, but ionic compounds can only conduct electricity if their ions are free to move.

15. Sodium Chloride

16. Potassium Chloride

17. Electrical Conductivity

18. Electrolyte An ionic compound whose aqueous solution conducts an electric current –NaCl, MgCl 2, KF

19. Energy and Ionic Bond Lattice energy: –The energy required to separate one mole of the ions of an ionic compound –Higher energy bonds = higher lattice energy

21. Homework 8.2 assessment P.236 #51-53; 67-73