Chemistry past paper corrections

Question 1

Describe what happens when a magnesium atom reacts with an oxygen atom

Answer 1

Magnesium atom loses electrons, oxygen atoms gains electrons, two electrons are transferred, magnesium ions and oxide ions are formed.

Question 2

Why could hydrogen be placed in group 1 or group 7?

Answer 2

• Can lose one electron to become stable
  -Forms diatomic molecules
  -Forms covalent bonds

Question 3

Explain how the reactivity of halogens increases going down group 2

Answer 3

The reactivity decreases going down group 7,so iodine is less reactive than bromine which is less reactive than chlorine, so chlorine can displace bromine and iodine, and bromine can displace iodine. E.g If potassium bromide reacts with chlorine, chlorine reacts with the potassium as it is more reactive, forms potassium chloride and bromine. The solution turns the colour of the isolated element ‘pushed out’ .

Question 4

what charge does a cathode attract?

Answer 4

positive charge (anode attracts negative)

Question 5

In what state is an element at a temperature in between their boiling and melting point?

Answer 5

Liquid

temperature < melting point = Solid
temperature is between melting and boiling points = Liquid
Given temperature > boiling point = Gas