1. Bonding Why do atoms bond? The octet rule – all atoms bond so they have 8 electrons in their outer shell, so that it is FULL.

2. Exceptions to this are: The Noble gases (group 8) Hydrogen Already have full outer shells The first shell can only fit two electrons in it

3. Types of bonding 1.Ionic 2.Covalent

4. 1 Ionic Metals and non- metals combine to make compounds How do they do this? They form ions

5. The metal loses electrons from its outer shell to form a positive ion Na Sodium atom (Na) Sodium ion (Na + )

6. How many electrons do atoms lose or gain? Metals Group 1 elements lose one electron to obtain a full octet e.g. Na [2,8,1] → Na + [2,8] Group 2 elements lose two electrons to obtain a full octet e.g. Mg [2,8,2] → Mg 2+ [2,8]

7. Non-metals Group 7 elements gain one electron to obtain a full octet e.g. Cl [2,8,7] → Cl - [2,8,8] Group 6 elements gain two electrons to obtain a full octet e.g. O [2,6] → O 2- [2,8] How many electrons do atoms lose or gain?

8. Properties of ionic compounds Very high melting and boiling points Brittle Conduct electricity when molten and in solution

9. Li Na K

10. Size

11. Li Na K Size Outer electron held more loosely

12. Li Na K Size Outer electron held more loosely Explains increasing reactivity

13. Ionic Bonding Ionic bonds form between metals and non- metals Metal atoms lose electrons to form positive ions Non-metal atoms gain electrons to form negative ions The oppositely charged ions attract one another

14. Sodium and Chlorine 11+ 17+ 11+ and 10- = 1+ Na + 17+ and 18- = 1- Cl - + -

15. Magnesium and Oxygen 12+8+ 12+ and 10- = 2+ Mg 2+ 8+ and 10- = 2- O 2- 2+ 2-

16. Magnesium and Chlorine 17+ and 18- = 1- Cl - 17+ and 18- = 1- Cl - 12+ and 10- = 2+ Mg 2+ 17+12+17+ - - 2+

17. Covalent Bonding Covalent bonds form between non-metal atoms Covalent bonds involve sharing a pair of electrons

18. Hydrogen and Hydrogen H H2H2 H

19. Nitrogen and Hydrogen (Ammonia) H H H N NH 3

20. Hydrogen and Oxygen H2OH2O H H O