1. Exam techniques by Dr Mike Thompson Head of Science (Rugby School)

2. Exam boards OCR CIE Edexcel AQA WJEC CIE (Pre-U)

3. Most common mistake Not reading the Question (RTQ) Answer the Question asked, and answer all parts!

4. Amount of substance Amount In moles Volume concentration Most common error in calculations is…..?

5. Amount of substance Amount In moles Volume in cm 3 concentration not dividing by 1000 to convert cm3 into dm3

6. Electronic configuration Most common error in calculations is…..?

7. Electronic configuration Selecting the wrong number and not using superscripts 1s2 2s2 2p6 3s2 3p6 4s2 3d4

8. Electronic configuration Selecting the wrong number and not using superscripts 1s2 2s2 2p6 3s2

9. Structure and bonding Ionic Covalent Metallic Most common errors involve using the wrong words

10. Ionic Compounds common error is writing the wrong formula…..? LiO MgCl CaOH

11. Ionic compounds common error is writing the wrong formula…..? LiO MgCl CaOH

12. Ionic compounds common error is writing the wrong formula…..?

13. Ion Formulae Group12345670 Charge on Ion 1+2+3+4+3-2-1-None formed Group NumberGroup NameExamples of Ions 1Alkali MetalsLi +, Na +, K +, Rb +, Cs + 2Alkaline Earth metalsBe 2+, Mg 2+, Ca 2+, Sr 2+ 7Halogens F -, Cl -, Br -, I - 0Noble GasesNo examples (full outer shell) Name of ion Oxides Hydroxide s SulfatesCarbonateNitrates Formula of ion O2-O2- OH - SO 4 2- CO 3 2- NO 3 -

14. Bonding and structure of sodium chloride (6) How many marks would this answer get? Ionic bonding with attraction between oppositely charged molecules Ionic lattice

15. Bonding and structure of sodium chloride (6) Any errors ? Ionic bonding with attraction between oppositely charged molecules Ionic lattice 2 marks

16. Bonding and structure of sodium chloride (6) Model answer Ionic bonding with electrostatic attraction between oppositely charged ions Giant Ionic lattice 3D arrangement of ions Na + ions surrounded by Cl - ions and vice versa

17. Describe the structure and bonding for H 2 and explain why it has a low b.p. -253 ⁰C (7) Break the Question into the different parts Structure: Bonding: Boiling point:

18. Describe the structure and bonding for H 2 and explain why it has a low b.p. -253 ⁰C (7) How many marks would this answer get? Structure: covalent molecule Bonding: between non-metals Boiling point: Low as little energy needed to break its covalent bonds

19. Describe the structure and bonding for H 2 and explain why it has a low b.p. -253 ⁰C (7) 1 mark Structure: covalent molecule Bonding: between non-metals Boiling point: Low as little energy needed to break its covalent bonds

20. Describe the structure and bonding for H 2 and explain why it has a low b.p. -253 ⁰C (7) Any errors ? Structure: covalent molecule Bonding: between non-metals Boiling point: Low as little energy needed to break its covalent bonds

21. Describe the structure and bonding for H 2 and explain why it has a low b.p. -253 ⁰C (7) Model answer Structure: simple covalent molecule Bonding: covalent bonding, shared pair of (negative) electrons, which are attracted to the positive nuclei of both atoms Boiling point: Low as little energy needed to break weak intermolecular forces

22. Covalent bonding Most common errors are… Thinking they involve metals (Na-Cl) Forgetting bonding electrons are in pairs Forgetting to add all the outer electrons for Halogens

23. Covalent bonding Most common errors are… Thinking they involve metals (Na-Cl) Forgetting to add all the outer electrons for Halogens

24. Covalent bonding How to get better Play with molymods

25. Covalent bonding How to get better Play with molymods

26. Covalent bonding How to get better Practise drawing dot-and-cross diagrams

27. Describe the structure & bonding in magnesium (5) Metallic Model answer

28. Describe the structure & bonding in magnesium (5) Metallic Model answer The diagram gets 2 marks Giant 3D lattice Metallic bonding Electrostatic attraction between positive metal ions and free delocalised electrons

29. Drawing Hydrogen bonds not showing all relevant dipoles not showing the lone pair not showing a bond angle of 180o Most common errors are

30. Drawing Hydrogen bonds not showing all relevant dipoles not showing the lone pair not showing a bond angle of 180o Most common errors are

31. Drawing Hydrogen bonds not showing all relevant dipoles not showing the lone pair not showing a bond angle of 180o Most common errors are

32. Drawing Hydrogen bonds Most common errors are

33. Empirical molecular structural displayed Types of formulae (ethanol)

34. Molecular formula of ethanol? Ratio of elements in a compound C 2 H 5 OH

35. Molecular formula of ethanol? Ratio of elements in a compound C 2 H 5 OH

36. Molecular formula of ethanol? Ratio of elements in a compound C 2 H 6 O

37. Ethanol – give its Functional Group? Alcohol 1 mark

38. Ethanol – give its Functional Group? 1 0 Alcohol 2 marks

39. Empirical formula of ethane? C2H6C2H6

40. Simplest whole number ratio of elements in a compound C 2 H 6

41. Empirical formula of ethane? Simplest whole number ratio of elements in a compound CH 3

42. Structural formula of ethanol?

43. CH 3 CH 2 HO

44. Structural formula of ethanol? CH 3 CH 2 OH

45. Displayed formula of ethanol

46. Displayed formula of ethanol show all the bonds including O-H

48. Displayed formula of ethanol

49. Displayed formula of ethanol?

51. Decimal places (2)

52. Decimal places (2)

53. Decimal places (2)

54. Use unambiguous language

57. Count bonds to carbon in organic compounds it always forms four bonds = tetravalent

58. 1 2 3 4 5

59. 1 2 3 4

60. Drawing a chiral carbon Most common errors…..? Not drawing in 3D Connecting the wrong atoms Not making the carbon look tetrahedral

61. Drawing a chiral carbon Most common errors…..? Not drawing in 3D Connecting the wrong atoms Not making the carbon look tetrahedral

62. Drawing a chiral carbon Most common errors…..? Not drawing in 3D Connecting the wrong atoms Not making the carbon look tetrahedral

63. Ionisation energy Definition (words) 1 st I.E. Energy needed to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous 1+ ions

64. Ionisation energy Definition (words) 1 st I.E. Energy needed to remove one mole of electrons from one mole of gaseous atoms to produce one mole of gaseous 1+ ions

65. Ionisation energy Definition (equation) 1 st I.E. M (g)  M + (g) + e - 1 mole 1 mole 1 mole

66. Mass spectrum Identify the molecular ion

67. Mass spectrum Identify the molecular ion M ?

68. Mass spectrum Identify the molecular ion M

69. Mass spectrum Identify the molecular ion M +

70. Mass spectrum Identify the molecular ion M + [M+1] + Due to carbon-13

71. Van der Waals’ forces Can you explain how these weakest of intermolecular forces are formed? (uneven distribution of electron clouds)

72. Van der Waals’ forces How are these weakest of intermolecular forces formed?

73. Van der Waals’ forces How are these weakest of intermolecular forces formed?

74. Van der Waals’ forces When revising don’t climb the walls like Helium! (take regular breaks)

75. Silly marks to lose Remember to add state symbols...when writing an equation for the standard enthalpy of formation of a compound, e.g. CO 2 C + O 2  CO 2 State symbols are often missed out and are essential to get the mark!

76. Silly marks to lose Remember to add state symbols...when writing an equation for the standard enthalpy of formation of a compound, e.g. CO 2 C (s) + O 2 (g)  CO 2 (g)

77. Practical / ISA / PSA Tips Titrations Results table FIT for purpose Rough1 st 2 nd Final / cm 3 Initial / cm 3 Titre / cm 3 Average / cm 3

78. Practical / ISA / PSA Tips Titrations Results table with (quantities & units) All values recorded to 2 decimal places Rough1 st 2 nd Final / cm 3 Initial / cm 3 Titre / cm 3 Average / cm 3

79. Practical / ISA / PSA Tips Titrations Results need to be concordant (within 0.10 cm 3 ) Rough1 st 2 nd Final / cm 3 Initial / cm 3 Titre / cm 3 Average / cm 3

80. Practical / ISA / PSA Tips Titrations Results table FIT for purpose (quantities &units) Rough1 st 2 nd Final / cm 3 24.30 48.3024.20 Initial / cm 3 0.0024.30 0.20 Titre / cm 3 24.3024.00 Average / cm 3 24.00

81. The End Thankyou for listening And good luck with your A-levels mat@rugbyschool.net

82. Useful websites http://www.chemguide.co.uk/ http://www.knockhardy.org.uk/sci.htm http://a-levelchemistry.co.uk/ http://www.chm.bris.ac.uk/motm/motm.htm http://chemnet.rsc.org/ http://www.rsc.org/learn-chemistry