1. Chemical Bonding

6. Why are noble gases unreactive? The valence shells of noble gases are shown here. Each noble gas has a fully filled valence shell.

10. Chemical Bonding What is chemical bonding? Chemical Bonding is the way in which atoms join together with each other. + sodium metal chlorine gas table salt

11. Chemical Bonding During a chemical reaction, atoms of the elements joined together to form ionic compound or covalent compound . Ionic Compound Covalent Compound

15. Formation of a Sodium Ion To attain an octet configuration, a sodium atom (Na) loses 1 valence electron. It forms a sodium ion (Na + ) and has a noble gas structure. sodium atom, Na Lose 1 electron sodium ion, Na + +

16. Formation of a Sodium Ion 11 p 11 e 12 n sodium atom, Na Lose one electron sodium ion, Na + + 11 p 10 e 12 n

18. Formation of Chlorine ion A chlorine atom (C l ) gains an electron to form a chloride ion (C l - ). The chloride ion has an octet configuration. Chlorine ion, C l - - Chlorine atom, Cl gains one electron

19. Formation of Chlorine ion Chlorine ion, C l - 17 p 17 e 18 n 17 p 18 e 18 n Chlorine atom gains one electron -

22. How do we show ionic bonding? We show it through the ‘dot and cross’ diagram . The diagram here shows the formation of an ionic bond in sodium chloride. C l Na

25. Example: Sodium chloride In a crystal of sodium chloride, Na+ and Cl- are held in fixed position by strong electrostatic force of attractions ( ionic bonds )

29. Electrical Conductivity – in solid sodium chloride Bulb does not light up. In solid, the ions are held in fixed position. They cannot move freely.

30. Electrical Conductivity – in molten sodium chloride However, if NaC l is heated until it melts… Bulb lights up.

32. Covalent Bonding

36. Covalent Bonding Y Y Y Y A B Which of the following diagrams obey the rule?