3.1.2 Group 2

Question 1

what are the elements in group 2 named sometimes

Answer 1

• alkaline earth metals
  > they are metals

Question 2

where are the 2 outer shell electrons found in g2 elements

Answer 2

• in the outer s sub-shell

Question 3

what happens to g2 elements in redox reactions

Answer 3

• metal atom oxidised
  > lose 2e- to form 2+ ion
• another species gains the 2e- and is reduced

Question 4

why are g2 elements reducing agents

Answer 4

• they cause another species to be reduced (it itself is oxidised)

Question 5

what are the 3 different redox reactions g2 undergo

Answer 5

• oxygen
• water
• dilute acids

Question 6

what is formed when g2 element reacts with oxygen

Answer 6

• metal + oxygen —> metal oxide

Question 7

what is oxidised + reduced in redox reaction of g2 elements with oxygen + give oxidation number

Answer 7

• metal oxidises 0 —> +2
• oxygen reduces 0 —> -2

Question 8

what is formed when g2 elements reacts with water

Answer 8

• metal + water —> metal hydroxide (alkaline) + hydrogen

Question 9

what is formed when g2 elements react with dilute acid

Answer 9

• metal + acid —> salt + hydrogen

Question 10

describe the trend in reactivity down g2

Answer 10

• reactivity increases down group
  > atomic radius inc + electron shielding inc
  > so nuclear attraction to outer shell electrons decrease
  > ionisation energy decrease
  > more easier to remove outer shell e- so more reactive

Question 11

describe the trend in reactivity down g2

Answer 11

• mp/bp decrease
  > atomic radius inc so weaker attraction between positive nucleus and delocalised electrons
  > metallic bonding also weaker due to weaker imf

Question 12

what happens when a g2 oxide reacts with water

Answer 12

• forms metal hydroxide (alkaline)

Question 13

are g2 hydroxides soluble

Answer 13

• slightly soluble in water

Question 14

describe the trend in solubility of hydroxides down g2

Answer 14

• solubility inc down group
  > releases more OH- + solution is more alkaline

Question 15

why are g2 compounds useful

Answer 15

• they are basic so can neutralise acids

Question 16

what is the use of g2 compounds in agriculture + equation

Answer 16

• calcium hydroxide (lime) added to fields to neutralise acid in soil / inc pH of acidic soil and forms neutral water
  Ca(OH)2 (s) + 2H+(aq) —> Ca2+(aq) + 2H2O(l)

Question 17

what is the use of g2 compounds in medicine

Answer 17

• used as antacids + treat acidic indigestion
• magnesium hydroxide or calcium carbonate used to neutralise excess stomach acid
  Mg(OH)2(s) + 2HCl(aq) —> MgCl2(aq) + 2H2O(l)

CaCO3(s) + 2HCl(aq) —> CaCl2 (aq) + H2O (l) + CO2(g)