1. IGCSE CHEMISTRY SECTION 2 LESSON 1

2. Content The iGCSE Chemistry course Section 1 Principles of Chemistry Section 2 Chemistry of the Elements Section 3 Organic Chemistry Section 4 Physical Chemistry Section 5 Chemistry in Society

3. Content Section 2 Chemistry of the Elements a)The Periodic Table b)Group 1 Elements c)Group 7 Elements d)Oxygen and Oxides e)Hydrogen and Water f)Reactivity Series g)Tests for ions and gases

4. Content Lesson 1 a)The Periodic Table b) Group 1 elements a)The Periodic Table 2.1 understand the terms group and period 2.2 recall the positions of metals and non-metals in the Periodic Table 2.3 explain the classification of elements as metals or non- metals on the basis of their electrical conductivity and the acid- base character of their oxides 2.4 understand why elements in the same group of the Periodic Table have similar chemical properties 2.5 understand that the noble gases (Group 0) are a family of inert gases and explain their lack of reactivity in terms of their electronic configurations. b) Group 1 elements — lithium, sodium and potassium 2.6 describe the reactions of these elements with water and understand that the reactions provide a basis for their recognition as a family of elements 2.7 describe the relative reactivities of the elements in Group 1 2.8 explain the relative reactivities of the elements in Group 1 in terms of distance between the outer electrons and the nucleus.

5. The Periodic Table

6. Groups

7. The Periodic Table Groups 1 2 3 4 5 6 7 8 (0)

8. The Periodic Table Periods

9. The Periodic Table Periods 12345671234567

10. The Periodic Table Alkali metals Alkaline Earth metals Transition metals Halogens Noble gases

11. The Periodic Table Sn = tin Group 4 Period 5

12. The Periodic Table Metals Non-metals

13. The Periodic Table The chemical elements are arranged in order of increasing atomic number

14. The Periodic Table Elements in the same group have the same number of electrons in their outermost shell. This is the same as the group number

15. The Periodic Table Elements in the same period have the same number of shells. This is the same as the period number

16. Metals and non-metals

17. More than ¾ of the elements in the Periodic Table are metals

18. Metals and non-metals More than ¾ of the elements in the Periodic Table are metals So what defines a metal?

19. Metals and non-metals Metals, such as gold, are good electrical conductors. This is because they have a giant structure in which electrons in the highest energy level are free to move through the entire structure.

20. Metals and non-metals Metals, such as gold, are good electrical conductors. This is because they have a giant structure in which electrons in the highest energy level are free to move through the entire structure. Non-metals, such as sulphur, are very poor conductors of electricity, or do not conduct at all.

21. Metals and non-metals Both metals and non-metals form oxides. For example: copper oxide CuO sulphur dioxide SO 2

22. Metals and non-metals Both metals and non-metals form oxides. For example: copper oxide CuO sulphur dioxide SO 2 Oxides of metallic elements are bases, those which dissolve in water form alkalis.

23. Metals and non-metals Both metals and non-metals form oxides. For example: copper oxide CuO sulphur dioxide SO 2 Oxides of metallic elements are bases, those which dissolve in water form alkalis. Oxides of non-metallic elements tend to be acids.

24. Metals and non-metals Metallic elements Oxides of metallic elements are solids Oxides of metallic elements are all bases Bases soluble in water are called alkalis Some bases are insoluble Non-metallic elements Many non-metallic oxides are gases, some are liquids and some solids Some are insoluble and neutral Most dissolve in water to form acids Combine with oxygen to form oxides

25. Metals and non-metals Non-metal oxides as acids: Sulphur dioxide + Water  Sulphurous acid SO 2 + H 2 O  H 2 SO 3

26. Metals and non-metals Metal oxides as bases: Base + Acid  Salt + Water eg. CuO + H 2 SO 4  CuSO 4 + H 2 O

27. Groups and chemical properties

28. The Group Number tells you how many electrons there are in the outer shell (orbit) of an element. For example, oxygen is in Group 6, so has 6 electrons in its outermost shell (2:6)

29. The Period Number tells you how many shells (orbits) there are around the nucleus. For example, Calcium is in Period 4, so will have 4 shells around the nucleus

30. The Period Number tells you how many shells (orbits) there are around the nucleus. For example, Calcium is in Period 4, so will have 4 shells around the nucleus

31. Groups and chemical properties why do elements in the same group of the Periodic Table have similar chemical properties

32. Groups and chemical properties why do elements in the same group of the Periodic Table have similar chemical properties It’s all to do with their electronic configuration.

33. Groups and chemical properties why do elements in the same group of the Periodic Table have similar chemical properties It’s all to do with their electronic configuration. In order to be stable, atoms need a full outer shell of electrons

34. Groups and chemical properties Elements in the same group have the same number of electrons in their outermost shell

35. Groups and chemical properties Atoms need to lose or gain electrons in order to become stable

36. Groups and chemical properties Metals lose their outer electron or electrons when they react, and non- metals gain

37. Groups and chemical properties The fewer electrons that need to be lost or gained, the more reactive the element

38. Groups and chemical properties The fewer electrons that need to be lost or gained, the more reactive the element

39. Groups and chemical properties Non-metals

40. Groups and chemical properties Group 1 elements lose one electron to become stable

41. Groups and chemical properties Group 1 elements lose one electron to become stable Group 2 elements lose two electrons to become stable

42. Groups and chemical properties Group 1 elements lose one electron to become stable Group 2 elements lose two electrons to become stable Group 3 elements lose three electrons to become stable

43. Groups and chemical properties Group 5 elements gain three electrons to become stable Group 6 elements gain two electrons to become stable Group 7 elements gain one electron to become stable

44. Groups and chemical properties The fewer electrons that need to be lost or gained, the more reactive the element

45. Groups and chemical properties Group 1 are the most reactive metals Group 7 are the most reactive non- metals

46. Groups and chemical properties What about the elements in Group 8 (0) ? Why are they so unreactive?

47. Groups and chemical properties What about the elements in Group 8 (0) ? Why are they so unreactive? Look at their electron configurations – can you see why they don’t react? 2 2:8 2:8:8

48. Groups and chemical properties What about the elements in Group 8 (0) ? Why are they so unreactive? Look at their electron configurations – can you see why they don’t react? 2 2:8 2:8:8 They already have full outer shells of electrons, so they don’t need to lose or gain any more. This is why they are called the inert gases. They don’t usually react. (They are also know as the rare or noble gases)

49. Content Lesson 1 a)The Periodic Table b) Group 1 elements a)The Periodic Table 2.1 understand the terms group and period 2.2 recall the positions of metals and non-metals in the Periodic Table 2.3 explain the classification of elements as metals or non- metals on the basis of their electrical conductivity and the acid- base character of their oxides 2.4 understand why elements in the same group of the Periodic Table have similar chemical properties 2.5 understand that the noble gases (Group 0) are a family of inert gases and explain their lack of reactivity in terms of their electronic configurations. b) Group 1 elements — lithium, sodium and potassium 2.6 describe the reactions of these elements with water and understand that the reactions provide a basis for their recognition as a family of elements 2.7 describe the relative reactivities of the elements in Group 1 2.8 explain the relative reactivities of the elements in Group 1 in terms of distance between the outer electrons and the nucleus.

50. Group 1 – The Alkali Metals

51. Alkali metals have a low density. The first three are less dense than water, and as a consequence they float.

52. Group 1 – The Alkali Metals Alkali metals have a low density. The first three are less dense than water, and as a consequence they float. Melting points and boiling points decrease as we go down the group

53. Group 1 – The Alkali Metals Alkali metals have a low density. The first three are less dense than water, and as a consequence they float. Melting points and boiling points decrease as we go down the group Reactivity increases as we go down the group

54. Group 1 – The Alkali Metals Alkali metals have a low density. The first three are less dense than water, and as a consequence they float. Melting points and boiling points decrease as we go down the group Reactivity increases as we go down the group All alkali metals react with non- metals to form ionic compounds.

55. Group 1 – The Alkali Metals Alkali metals have a low density. The first three are less dense than water, and as a consequence they float. Melting points and boiling points decrease as we go down the group Reactivity increases as we go down the group They all lose one electron to form a metal ion with the charge +1

56. Group 1 – The Alkali Metals Alkali metals have a low density. The first three are less dense than water, and as a consequence they float. Melting points and boiling points decrease as we go down the group Reactivity increases as we go down the group They all lose one electron to form a metal ion with the charge +1 Ionic compounds are white solids which form colourless solutions

57. Group 1 – The Alkali Metals Reaction with water The alkali metals react with water to produce soluble hydroxides (alkalis) and hydrogen. eg. Potassium + Water  Potassium + Hydrogen hydroxide 2K (s) + 2H 2 O (l)  2KOH (aq) + H 2(g)

58. Group 1 – The Alkali Metals Reaction with water The alkali metals react with water to produce soluble hydroxides (alkalis) and hydrogen. eg. Potassium + Water  Potassium + Hydrogen hydroxide 2K (s) + 2H 2 O (l)  2KOH (aq) + H 2(g) 2Na (s) + 2H 2 O (l)  2NaOH (aq) + H 2(g)

59. Group 1 – The Alkali Metals Reaction with water Going down the group, the alkali metals become more reactive, and react more vigorously with water. They float, may melt and the hydrogen gas produced may ignite Lithium reacts gently, sodium more violently, and potassium so violently that it melts and bursts into flames.

60. Group 1 – The Alkali Metals Reaction with water

61. Group 1 – The Alkali Metals Why does the reactivity increase going down the group?

62. Group 1 – The Alkali Metals Why does the reactivity increase going down the group? It’s all to do with the number of shells around the nucleus!

63. Group 1 – The Alkali Metals Why does the reactivity increase going down the group? It’s all to do with the number of shells around the nucleus! 2:1 2:8:1 2:8:8:1 Going down the group the atomic radius gets bigger due to extra full shells of electrons. The outer electron is further from the nucleus and so less strongly held.

64. Group 1 – The Alkali Metals Why does the reactivity increase going down the group? It’s all to do with the number of shells around the nucleus! 2:1 2:8:1 2:8:8:1 This means that the outer electron is more easily lost, the +1 ion is more easily formed, and so the elements are more reactive going down the group.

65. End of Section 2 Lesson 1 In this lesson we have covered: The Periodic Table Group 1 – The Alkali Metals