Group 2 and 7 revision

For each of the 11 statements name the substance An insoluble group 2 sulphate A silver halide that forms an insoluble cream precipitate on reaction with dilute ammonia solution. This then dissolves in concentrated ammonia. An insoluble group 2 hydroxide A white coloured silver halide A gas that forms hypochlorite (HClO) and HCl when bubbled through water. A substance that will form an orange liquid when it reacts with bromide A group 1 carbonate that does NOT decompose on heating An ion that reacts with sulphuric acid to produce a purple solid A brown toxic acidic gas An ion that reacts with sulphuric acid to produce an orange liquid Magnesium reacts with hot water to make

For each of the 11 statements name the substance BaSO4 An insoluble group 2 sulphate A silver halide that forms an insoluble cream precipitate on reaction with dilute ammonia solution. This then dissolves in concentrated ammonia. AgBr Mg(OH)2 An insoluble group 2 hydroxide AgCl Cl2 A white coloured silver halide A gas that forms hypochlorite (HClO) and HCl when bubbled through water. F2 Cl2 Li2CO3 A substance that will form an orange liquid when it reacts with bromide A group 1 carbonate that does NOT decompose on heating I- NO2 An ion that reacts with sulphuric acid to produce a purple solid A brown toxic acidic gas Br- MgO An ion that reacts with sulphuric acid to produce an orange liquid Magnesium reacts with hot water to make

Unit 2 – Group 2/7 elements Revision B4 Mid End C Can I describe the trends in reactivity for the group 2 and group 7 elements? Can I explain these trends using keywords? A Can I solve independently group 2 and 7 reactivity problems using ionic equations? B Do not just do ticks and crosses – traffic lights – put a picture of traffic lights on the PPT

Write balanced ionic equations with state symbols for the reactions that happen. Explain why they happen. F2 Cl- F2 I- Cl- Br2 Br2 I-

Write balanced ionic equations with state symbols for the reactions that happen. Explain why they happen. F2 Cl- F- Cl2 2 2 g aq aq g F2 I- F- I2 2 2 g aq aq s Cl- Br2 Br2 Br- I- I2 2 2 l aq aq s

Simple answer: a more reactive halogen displaces another less reactive halogen in an ionic compound. F2 Cl- F2 I- Cl- Br2 Br2 I-

Unit 2 – Group 2/7 elements Revision B4 Mid End C Can I describe the trends in reactivity for the group 2 and group 7 elements? Can I explain these trends using keywords? A Can I solve independently group 2 and 7 reactivity problems using ionic equations? B Do not just do ticks and crosses – traffic lights – put a picture of traffic lights on the PPT

Write down a description and explanation for two of these trends Melting point going down group 2 Reactivity going down group 2 Boiling point going down group 7 Oxidising power of group 7 halogen ATOMS or MOLECULES Reducing power of group 7 ANIONS (challenge question)

Write down a description and explanation for two of these trends Melting point going down group 2 Decreases owing to larger ionic radius and lower charge density on cation. Therefore the attraction between the cation and the sea of delocalised electrons is weaker

Write down a description and explanation for two of these trends Reactivity going down group 2 Increases as the metal is easier to oxidise. This is because the attraction between the nucleus and the outershell electron is weaker owing to more electron shielding and an increased atomic radius

On a post it note write down a description and explanation for two of these trends Boiling point going down group 7 Increases as there are more electrons. Therefore there is an increase in the London force (induced dipole) between molecules.

Write down a description and explanation for two of these trends Reducing power of group 7 ANIONS Increases as there is weaker attraction between the nucleus and the outermost electron gets weaker and so the outermost electron is more readily given to another species, thereby reducing it.

Write down a description and explanation for two of these trends Oxidising power of group 7 halogen ATOMS or MOLECULES Decreases because the electronegativity decreases going down group 7 from F to I

Unit 2 – Group 2/7 elements Revision B4 Mid End C Can I describe the trends in reactivity for the group 2 and group 7 elements? Can I explain these trends using keywords? A Can I solve independently group 2 and 7 reactivity problems using ionic equations? B Do not just do ticks and crosses – traffic lights – put a picture of traffic lights on the PPT

A* A B A student wants to make magnesium oxide. Explain using a symbol equation how this can be done using magnesium and water. A scientist has prepared a white coloured silver halide. Identify the halide ion. Explain using symbol equations how a solution of sodium chlorate (I) can be prepared. Explain using oxidation numbers and symbol equations that the iodide ion has greater reducing power than bromide and chloride A chemist wants to make a solution of hypochlorite (HOCl) to disinfect swimming pool. He has chloride ions, fluorine and water. Explain using 2 symbol equations how she could do this. You do not need to explain how any of the substances need to be separated. A

A B A* A Mark scheme H2O (g) + Mg (s)  MgO (s) + H2 (g) 2. chloride NaOH (aq) + Cl2 (g)  NaClO3 (aq) + NaCl (aq) + H2O (l) ------ COLD 4. H2SO4 + NaCl  HCl + NaHSO4 --- S goes from +6 to +6 H2SO4 + HBr  Br2 + SO2 + H2O --- S goes from +6 to +4 H2SO4 + HI  I2 + H2S + H2O ---- S goes from +6 to -2 Therefore I- is the strongest reducing agent because sulphur has become more negative in oxidation number. 5. F2 (g) + Cl-(aq)  F- (aq) + Cl2 (g) H2O(l) + Cl2 (g)  HClO (aq) + HCl (aq) Mark scheme A