Bonding

1. + Bonding - H Cl X K Warne

2. Bonding Objectives: At the end of this unit you should be able to:- • Explain how metallic bonding determines the prosperities of metals • State/explain (understand) the significance of valence electrons • State the conditions for covalent bonding. • Explain the properties of substances (simple and giant covalent) in terms of their bonding and structure. • Know (state) conditions for ionic bonding. • Name chemical compounds correctly. • List the characteristics of different states of matter.

3. Covalent bond A shared PAIR of electrons. • Formed between ......................... • Common Ions KNOW formulae; egsulphate ion SO42- • Diatomic Molecules; ....2, ....2, ....2, ....2, ....2, .....2, ......2, • Pure covalent bonds have .....................SHARING of the electrons. Hydrogen molecule Single hydrogen atom H • A shared pair of electrons = a single covalent bond In covalent substances all the electrons are strongly held in the bonds and so the substance ............................ conduct electricity.

4. Covalent bond A shared PAIR of electrons. • Formed between non metals. • Common Ions KNOW formulae; egsulphate ion SO42- • Diatomic Molecules; H2, O2, F2, Cl2, Br2, I2, N2, • Pure covalent bonds have EQUAL SHARING of the electrons. Hydrogen molecule Single hydrogen atom x H • H H • H H A shared pair of electrons = a single covalent bond This is a PURE COVALENT, SINGLE BOND! In covalent substances all the electrons are strongly held in the bonds and so the substance will NOT conduct electricity.

5. x x x x x x x x Couper Notation O O x x x x O O x x x x O O x x x x x x x x “Dot Cross Diagrams” - Lewis & Couper Notation Multiple Bonds: Two atoms can share more than one pair of electrons. Lewis Diagrams Chemical Formulae O Name: Oxygen x x x x x O x O x x x x x x Draw similar diagrams for all the other diatomic molecules.

6. x x x x x x x x Couper Notation O O x x x x O O x x x x O=O x x x x x x x x x x x x x O x O x x x x x x “Dot Cross Diagrams” - Lewis & Couper Notation Multiple Bonds: Two atoms can share more than one pair of electrons. Lewis Diagrams Chemical Formulae O2 Name:Oxygen Nitrogen (N2) has a triple bond draw Lewis & Couper diagrams for nitrogen. Draw similar diagrams for all the other diatomic molecules.

7. N2

8. N2

9. Diatomic Molecules • F2, Cl2, Br2,

10. Diatomic Molecules • F2, Cl2, Br2,

11. Covalent Molecules • CH4, H2O, NH3, • CO2, NH4+,

12. Covalent Molecules • CH4, H2O, NH3, • CO2, NH4+,

13. ● ● O H H+ ●  ● + x ● ● x H

14. + ● ● ● ● O O H H+ H H ●  ● ● ● + x x ● ● x ● ● x H H

15. Methane - CH4 All the bonds are identical and the molecule has a TETRAHEDRAL SHAPE

18. Fluorine oxide (OF2 ) Oxygen atom Fluorine atom   X F   O X  X X   X X

19. Fluorine oxide (OF2 ) Oxygen atom Fluorine atom   X F   O X  X X   X X   F   F      X O F F   O X  X X   X X Couper Structure Lewis structure By sharing pairs of electrons all bonding atoms now effectively have a full outer shell (8 electrons).

20. Boron tri fluoride (BF3)

21. Boron tri fluoride (BF3) F     F   F      B    X  B   F F F X  X    Three shared pairs Trigonal Planar structure By sharing pairs of electrons all bonding atoms now effectively have a full outer shell (8 electrons).

23.             F F F F F F                               S     Cl         X Cl     Cl P X  X     X X

31. H C N

33. SO2 Lewis structure SO2 Couper structure x x xx S H S O xx x x x x x O x O  Cl  O O           Two double bonds Two double bonds F Be F F Be F x x Linear shape Two shared pairs

34. Triple bonds

35. Triple bonds

36. Co-ordinate bonding • Co-ordinate or Dative covalent bonding

37. Co-ordinate bonding • Co-ordinate or Dative covalent bonding

38. Lewis acid & base • Try and draw the other two and identify the coordinate bonds. H3NBF3 Cu(NH3)4+ Cu(H2O)62+

39. Lewis acid & base • Try and draw the other two and identify the coordinate bonds. Cu H3NBF3 Cu(NH3)4+ Cu(H2O)62+

40. Cu(NH3)4+

41. Electronegativity The ability/power to attract electrons in a bond.

42. Electronegativity in a Group Group 1 Electronegativity ………………… from TOP to BOTTOM in a group as the number of ………… increase bonding electrons (outer) are ………… from nucleus and therefore ………… strongly attracted. Electronegativity DECREASES H Li Na

43. Electronegativity in a Group Group 1 Electronegativity DECREASES from TOP to BOTTOM in a group as the number of shells increase bonding electrons (outer) are further from nucleus and therefore LESS strongly attracted. Electronegativity DECREASES H Li Na

44. Electronegativity Trends Group 1 2 3 4 5 6 7 8 Electronegativity………………..from LEFT to RIGHT as the number of protons in the nucleus…………………….andbonding electrons (outer) are more strongly attracted. He H Li Be B C N O F Ne Na Mg Al Si P S ClAr ElectronegativityDECREASESfrom TOP to BOTTOM in a group as the number of shells increasebonding electrons (outer) are LESS strongly attracted.

45. Electronegativity Trends Group 1 2 3 4 5 6 7 8 ElectronegativityINCREASESfrom LEFT to RIGHT as the number of protons in the nucleusINCREASES and bonding electrons (outer) are more strongly attracted. He H Li Be B C N O F Ne Na Mg Al Si P S ClAr ElectronegativityDECREASESfrom TOP to BOTTOM in a group as the number of shells increasebonding electrons (outer) are LESS strongly attracted.

46. Electronegativity

47. VALENCY – BOHR DIAGRAMS Valence electrons – those in ……………. shell. Valency – ……………….. of electrons ……..….. or ……….... to have a FULL valence level. (Outer shell) He H Li Be B C N O F Ne Na Mg Al Si P S Cl Ar

48. VALENCY – Bonds Formed Valence electrons – those in outershell = group number. • Valency – number of electrons lost or gained to have a FULL valence level. (Outer shell) =number of bonds formed by an element. NON - METALS METALS He H Li Be B C N O F Ne

49. Polar Covalent Bond Each side of the molecule has a small charge due to the electrons being …………………………..SHARED. + - Electron density diagram - more electron density around the chlorine H Cl X A ……………(two poles) has been created. • Chlorine has a …………………..electro negativity than hydrogen. The “” symbol (delta) stands for small amount or small change. > This type of bonding exists when there is a relatively large …………………….. inelectronegativity between the bonding atoms.

50. Polar Covalent Bond Each side of the molecule has a small charge due to the electrons being UNEQUALLY SHARED. + - Electron density diagram - more electron density around the chlorine H Cl X A dipole (two poles) has been created. • Chlorine has a higher electro negativity than hydrogen. The “” symbol (delta) stands for small amount or small change. > This type of bonding exists when there is a relatively large difference inelectronegativity between the bonding atoms.