This document discusses covalent bonds and how they differ from ionic bonds. Covalent bonds involve sharing electrons between atoms rather than transferring electrons. Chlorine atoms form a covalent bond by each atom sharing an electron pair, allowing both atoms to achieve a full outer shell or octet of electrons. Covalent bonds typically form between nonmetal atoms in groups 3-6 of the periodic table, which have incomplete outer shells and can share electrons to achieve full shells. Carbon is particularly important for life because it can form up to four covalent bonds, allowing for complex carbon chains and structures like DNA and proteins.

1. Covalent BondsUnit 11

2. Covalent BondsInvolve sharing outer energy level electrons.

3. How Are They Different Than Ionic?Ionic bonds work by electromagnetic attraction. A positively charged ion is attracted to a negative ion.Covalent bonds work by sharing electrons. They do not have charges, but are hard to separate due to this sharing.

4. ClClHow will two chlorine atoms react?

5. ClClEach chlorine atom wants to gain one electron to achieve an octet

6. ClCl

7. ClCl

8. ClCl

9. ClCloctet

10. ClCloctetcircle the electrons foreach atom that completestheir octets

11. ClClThe octet is achieved byeach atom sharing theelectron pair in the middlecircle the electrons foreach atom that completestheir octets

12. ClClThe octet is achieved byeach atom sharing theelectron pair in the middlecircle the electrons foreach atom that completestheir octets

13. ClClThis is the bonding paircircle the electrons foreach atom that completestheir octets

14. ClClSingle bonds are abbreviatedwith a dashcircle the electrons foreach atom that completestheir octets

15. ClClThis is the chlorine molecule,Cl2circle the electrons foreach atom that completestheir octets

16. Covalent BondsEach oxygen has 6 valence electrons and wants two more to have a full octet.6 electrons6 electrons

17. Covalent BondsIf one oxygen shares two electrons with the other, the other has a full octet.8 electrons – happy!4 electrons left

18. Covalent BondsBut, then the other oxygen is short, so it pulls them back.Now the other oxygen shares 2 electrons4 electrons left8 electrons – happy!

19. Covalent BondsThus, by each of them sharing two electrons back and forth, they both are at the full octet simultaneously.8 electrons8 electrons

20. OO

21. OO

22. OO

23. OO

24. OOBoth electron pairs are shared.

25. OOBoth electron pairs are shared.

26. So Who Covalently Bonds?Alkaline or Alkali Earth Metals do not form covalent bonds!Also Halogens are rarely covalently bonded.Mostly it is non-metals in groups 3,4,5, and 6

27. Electron Distribution... C.Valence Electrons: 4Electrons occur in 4 fours separated as far apart as possible

28. Electron Distribution..... N C..Valence Electrons: 4 5Electrons occur in 4 fours separated as far apart as possible

29. Electron Distribution..... N C..O..Valence Electrons: 4 5 6Electrons occur in 4 fours separated as far apart as possible

30. Electron Distribution..... N C..O..Valence Electrons: 4 5 6Electrons occur in 4 fours separated as far apart as possibleSecret Question: Why do electrons first fill orbitals one at a time before pairing up?

31. Electron Distribution..... N C..O..Valence Electrons: 4 5 6Electrons occur in 4 fours separated as far apart as possibleSecret Question: Why do electrons first fill orbitals one at a time before pairing up?It is because electrons repel each other and want to be as far apart as possible.

32. Exception to Octet RuleBoron only has 3 valence electrons, so it is impossible to get to eight via covalent bondingWithout 4 valence electrons, the shape of the molecule flattens out.BH3B...

33. Single BondEthane is C2H6

34. Double BondEthene is C2H4

35. Triple BondAcetylene is C2H2

36. Quadruple Bond???Can not occur, because the last bond can not bend all the way around.Too far to bendToo far to bendEspecially since triple bonds are so rigid

37. Possible Covalent BondsOnly where single electrons are located, can covalent bonds be made.Carbon has 4 single electrons, thus it can make 4 bonds.Nitrogen has 3 single electrons, thus it can make 3 bonds.Oxygen has 2 single electrons, thus it can make 2 bonds.

38. Double Bonds RevisitedSince Oxygen can make two bonds, and Carbon can make four, it makes for some interesting combinations.

39. Why Carbon is the Key to LifeIt is precisely because carbon can make 4 bonds, as well as, double and triple bonds, that makes it so critical to life.Carbon chains can form virtually every formation possible.

40. DNA and the building blocks for lifeCarbon, plus two other flexible elements, oxygen and nitrogen form the backbone of DNADNA contains the genetic code for the building of life out of the largest of all molecules, proteins.

41. Proteins are the largest molecules known