C8

Question 1

Describe and explain the trend down the group in reactivity of Group 2 elements [5]

Answer 1

• reactivity increases
• atomic radii increase OR there are more shells
• there is ‘more’ shielding
• nuclear attraction decreases OR increased shielding and distance outweigh increased nuclear charge
• easier to remove (outer) electrons OR ionisation energy decreases

Question 2

Explain why barium is more reactive than calcium (4)

Answer 2

barium atoms are larger
barium atoms have more shielding
this outweighs increase in nuclear charge
barium electrons are lost more easily / ionisation energy decreases

Question 3

State and explain trend in boiling points of chlorine, bromine, iodine (3)

Answer 3

• boiling points increase down the group
• greater number of electrons OR stronger intermolecular forces
• more energy needed to break intermolecular forces

Question 4

Chlorine is used in water treatment

State one adv and one disadvantage

Answer 4

Adv: removes / kills bacteria OR kills germs OR kills micro-organisms OR makes it safe to drink OR sterilises water

Disadvantage: it is toxic OR poisonous OR could form chlorinated hydrocarbons