1.13 Group 1: the alkali metals
6 exam questions worth 13 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which gas is produced when sodium reacts with water?
Choose one answer.
Correct Not quite: the answer is Hydrogen
Mark scheme
B
Model answer
B: sodium + water → sodium hydroxide + hydrogen.
Write a balanced symbol equation for the reaction of potassium with water.
Mark scheme
- correct formulae: K, H2O, KOH, H2 (1)
- balanced: 2K + 2H2O → 2KOH + H2 (1)
Model answer
2K + 2H2O → 2KOH + H2
Explain why potassium is more reactive than sodium.
Mark scheme
- potassium atoms have more shells / are larger (1)
- outer electron is further from the nucleus / more shielding (1)
- weaker attraction between nucleus and outer electron (1)
- so the outer electron is lost more easily (1)
Model answer
A potassium atom has one more shell than a sodium atom, so its outer electron is further from the nucleus and more shielded. The attraction to the nucleus is weaker, so the outer electron is lost more easily, making potassium more reactive.
A small piece of sodium is added to a trough of water.
Give two things you would see.
Mark scheme
any two from:
- floats (1)
- fizzes / bubbles (1)
- melts into a ball (1)
- moves around the surface (1)
- gets smaller / disappears (1)
Model answer
The sodium floats, fizzes, melts into a ball and whizzes around until it disappears.
Caesium is near the bottom of Group 1.
Predict how caesium reacts with water and name the products.
Mark scheme
- reacts very violently / explosively (1)
- caesium hydroxide (1)
- hydrogen (1)
Model answer
Caesium reacts explosively with water, forming caesium hydroxide and hydrogen.
Explain why Group 1 metals are stored under oil.
Mark scheme
- to stop them reacting with oxygen / water (vapour) in the air (1)
Model answer
The oil keeps out air, so the metals cannot react with oxygen and water vapour.
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