1. 1 Chapter 4 Covalent bonding

2. 2 How does H 2 O form? l Oxygen has 6 valence electrons. l Does Hydrogen give up its one electron?

3. 3 How about H 2 ? ++ l The nuclei repel because of positive charges l But they are attracted to electrons l They share the electrons

4. 4 Covalent Bonds l Formed by the attraction of two atoms for a shared pair of electrons. l Neither atom will have a charge. l Molecule - an uncharged group of two or more atoms held together by covalent bonds.

5. 5 Covalent Bonds l Do nonmetals gain or lose electrons to attain noble gas configuration? l Can two or more nonmetals form a bond? YES!

6. 6 How? BY SHARING ELECTRONS

7. 7 Covalent bonding l Fluorine has seven valence electrons F

8. 8 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven FF

9. 9 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons FF

10. 10 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons FF

11. 11 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons FF

12. 12 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons FF

13. 13 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons FF

14. 14 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons l Both end with full orbitals FF

15. 15 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons l Both end with full orbitals FF 8 Valence electrons

16. 16 Covalent bonding l Fluorine has seven valence electrons l A second atom also has seven l By sharing electrons l Both end with full orbitals FF 8 Valence electrons

17. 17 Single Covalent Bond l A sharing of two valence electrons. l Occurs between nonmetals and Hydrogen. l Form molecules, NOT ionic compounds.

18. 18 How to show how they formed l It’s like a jigsaw puzzle. l I have to tell you what the final formula will be. l You put the pieces together to end up with the right formula.

19. 19 Water H O Each hydrogen has 1 valence electron Each hydrogen wants 1 more The oxygen has 6 valence electrons The oxygen wants 2 more They share to make each other happy

20. 20 Water l Put the pieces together l The first hydrogen is happy l The oxygen still wants one more H O

21. 21 Water l The second hydrogen attaches l Every atom has full energy levels H O H

22. 22 Multiple Covalent Bonds Atoms can share more than one pair of electrons - single covalent bonds (2 e - ) - double covalent bonds (4e - ) - triple covalent bonds (6e - )

23. 23 Carbon dioxide l CO 2 - Carbon is central atom ( I have to tell you) l Carbon has 4 valence electrons l Wants 4 more l Oxygen has 6 valence electrons l Wants 2 more O C

24. 24 Carbon dioxide l Attaching 1 oxygen leaves the oxygen 1 short and the carbon 3 short O C

25. 25 Carbon dioxide l Attaching the second oxygen leaves both oxygen 1 short and the carbon 2 short O C O

26. 26 Carbon dioxide l The only solution is to share more O C O

27. 27 Carbon dioxide l The only solution is to share more O C O

28. 28 Carbon dioxide l The only solution is to share more O CO

29. 29 Carbon dioxide l The only solution is to share more O CO

30. 30 Carbon dioxide l The only solution is to share more O CO

31. 31 Carbon dioxide l The only solution is to share more O CO

32. 32 Carbon dioxide l The only solution is to share more l Requires two double bonds l Each atom gets to count all the atoms in the bond O CO

33. 33 Carbon dioxide l The only solution is to share more l Requires two double bonds l Each atom gets to count all the atoms in the bond O CO 8 valence electrons

34. 34 Carbon dioxide l The only solution is to share more l Requires two double bonds l Each atom gets to count all the atoms in the bond O CO 8 valence electrons

35. 35 Carbon dioxide l The only solution is to share more l Requires two double bonds l Each atom gets to count all the atoms in the bond O CO 8 valence electrons

36. 36 How to draw them l Add up all the valence electrons. l This is the number you have to work with l Use the guess and check method until all atoms have 8 electrons (except H and He) l Some electrons will be shared

37. 37 Examples l NH 3 – N is central l N - has 5 valence electrons l H - has 1 valence electrons N H

38. 38 Examples l HCN C is central atom l N - has 5 valence electrons l C - has 4 valence electrons l H - has 1 valence electrons l Total of 10 electrons

39. 39 Another way of indicating bonds l Often use a line to indicate a bond l Called a structural formula l Each line is 2 valence electrons HHO HHO

40. 40 Structural Examples H CN C O H H l C has 8 electrons because each line is 2 electrons l Ditto for N l Ditto for C here l Ditto for O

41. 41 Interparticle Forces

42. 42 Interparticle Forces l Forces in molecular compounds are weaker than those in ionic compounds.

43. 43 Molecular Compounds l Usually not soluble in water l Do not conduct electricity well (Why not?) l Usually liquids or gases at room temperature