1. 1
   A fireworks manufacturer is investigating why lithium, sodium and potassium compounds produce different flame colours when burned, and why these three metals are grouped together in Group 1 of the periodic table.

   (a)

   What do lithium, sodium and potassium have in common that places them all in Group 1?

   [1 mark]

   • AThey each have 7 electrons in their outer shell
   • BThey each have 1 electron in their outer shell
   • CThey are all noble gases
   • DThey each have the same total number of electrons

   (b)

   The manufacturer also observes that potassium reacts far more vigorously with water than lithium does, even though both are Group 1 metals.
   
   Which statement correctly explains this difference in reactivity?

   [1 mark]

   • APotassium's outer electron is further from the nucleus and more easily lost than lithium's, so potassium is more reactive
   • BLithium has more protons than potassium, making it less reactive
   • CPotassium has a full outer shell, unlike lithium
   • DReactivity in Group 1 does not depend on atomic structure

   (c)

   Explain, in terms of electronic structure, why reactivity increases going down Group 1 from lithium to sodium to potassium.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A chemistry technician is preparing a demonstration for a science outreach event, in which a small piece of sodium is dropped into a trough of water. The sodium moves rapidly across the surface, fizzes vigorously, and eventually disappears completely, while a gas is given off.

   (a)

   A chemistry technician preparing a demonstration for a science outreach event drops a small piece of sodium into a trough of water. The sodium moves rapidly across the surface, fizzes, and eventually disappears, and a gas is produced that pops with a lit splint.
   
   What gas is produced when sodium reacts with water?

   [1 mark]

   • AOxygen
   • BCarbon dioxide
   • CHydrogen
   • DChlorine

   (b)

   The technician then tests the resulting solution in the trough with universal indicator. What colour change would be expected, and what does this show about the solution formed?

   [1 mark]

   • AThe indicator turns red, showing the solution is acidic
   • BThe indicator turns colourless, showing no reaction occurred
   • CThe indicator stays green, showing the solution is neutral
   • DThe indicator turns purple/blue, showing the solution is alkaline

   (c)

   Write a word equation for the reaction between sodium and water, and describe two observations from the demonstration that show this is a vigorous chemical reaction.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A safety inspector at a chemical storage facility is reviewing why samples of lithium, sodium and potassium are kept stored under oil in sealed containers rather than being left exposed to the open air.

   (a)

   Describe what happens when a Group 1 metal such as sodium is exposed to oxygen in the air, and explain why storing it under oil prevents this.

   [3 marks]

   (b)

   The inspector also wants staff to understand what would happen if potassium, rather than lithium, were accidentally exposed to both air and water at the same time. Describe and explain the difference in how vigorously lithium and potassium would react with oxygen and with water, linking your answer to their positions in Group 1.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A science writer is preparing a general-audience article explaining the trends and properties of the Group 1 alkali metals, focusing on how their electronic structure explains both physical properties such as melting point and chemical reactivity.

   (a)

   A science writer preparing an article on the alkali metals wants to explain their key trends to a general audience. Describe the general physical and chemical properties of Group 1 metals, and explain, using electronic structure, why melting point decreases going down the group while reactivity with water increases.

   [6 marks]

   (b)

   The science writer wants to include a section evaluating a common misconception: that all Group 1 metals are equally dangerous to handle. Evaluate this claim by comparing the hazards of handling lithium with the hazards of handling potassium, and explain your reasoning using their chemical properties.

   [6 marks]

   Total for question 4: 12 marks

End of questions