2. Ionic Bonding What happens to the e-?

3. Electron Dot diagrams l A way of keeping track of valence electrons. l How to write them l Write the symbol. l Put one dot for each valence electron l Don’t pair up until they have to X

4. The Electron Dot diagram for Nitrogen l Nitrogen has 5 valence electrons. l First we write the symbol. N l Then add 1 electron at a time to each side. l Until they are forced to pair up.

5. Write the electron dot diagram for l Na l Mg lClC lOlO lFlF l Ne l He

6. Electron Configurations for Cations l Metals lose electrons to attain noble gas configuration. l They make positive ions. l If we look at electron configuration it makes sense. l Na 1s 2 2s 2 2p 6 3s 1 - 1 valence electron l Na + 1s 2 2s 2 2p 6 -noble gas configuration

7. Electron Dots For Cations l Metals will have few valence electrons Ca

8. Electron Dots For Cations l Metals will have few valence electrons l These will come off Ca

9. Electron Dots For Cations l Metals will have few valence electrons l These will come off l Forming positive ions Ca +2

10. Electron Configurations for Anions l Nonmetals gain electrons to attain noble gas configuration. l They make negative ions. l If we look at electron configuration it makes sense. l S 1s 2 2s 2 2p 6 3s 2 3p 4 - 6 valence electrons l S -2 1s 2 2s 2 2p 6 3s 2 3p 6 -noble gas configuration.

11. Electron Dots For Anions l Nonmetals will have many valence.electrons. l They will gain electrons to fill outer shell. P P -3

12. Stable Electron Configurations l All atoms react to achieve noble gas configuration. l Noble gases have 2 s and 6 p electrons. l 8 valence electrons. l Also called the octet rule. Ar

13. Ionic Bonding l Anions and cations are held together by opposite charges. l Ionic compounds are called salts. l Simplest ratio is called the formula unit. l The bond is formed through the transfer of electrons. l Electrons are transferred to achieve noble gas configuration.

14. Ionic Bonding NaCl

15. Ionic Bonding Na + Cl -

16. Ionic Bonding l All the electrons must be accounted for! CaP

17. Ionic Bonding CaP

18. Ionic Bonding Ca +2 P

19. Ionic Bonding Ca +2 P Ca

20. Ionic Bonding Ca +2 P -3 Ca

21. Ionic Bonding Ca +2 P -3 Ca P

22. Ionic Bonding Ca +2 P -3 Ca +2 P

23. Ionic Bonding Ca +2 P -3 Ca +2 P Ca

24. Ionic Bonding Ca +2 P -3 Ca +2 P Ca

25. Ionic Bonding Ca +2 P -3 Ca +2 P -3 Ca +2

26. Ionic Bonding Ca 3 P 2 Formula Unit

27. Properties of Ionic Compounds l Crystalline structure. l A regular repeating arrangement of ions in the solid. l Ions are strongly bonded. l Structure is rigid. l High melting points- because of strong forces between ions.

28. Crystalline structure

29. Do they Conduct? l Conducting electricity is allowing charges to move. l In a solid, the ions are locked in place. l Ionic solids are insulators. l When melted, the ions can move around. l Melted ionic compounds conduct. l First get them to 800ºC. l Dissolved in water they conduct.

30. Metallic Bonds l How atoms are held together in the solid. l Metals hold onto there valence electrons very weakly. l Think of them as positive ions floating in a sea of electrons.

31. Sea of Electrons ++++ ++++ ++++ l Electrons are free to move through the solid. l Metals conduct electricity.

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

33. Malleable ++++ ++++ ++++

34. ++++ ++++ ++++ l Electrons allow atoms to slide by.

35. Ionic solids are brittle +-+- + - +- +-+- + - +-

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