This question is about Group 1 elements - AQA - GCSE Chemistry - Question 4 - 2021 - Paper 1
Question 4
This question is about Group 1 elements.
Give two observations you could make when a small piece of potassium is added to water.
1
2
Complete the equation for th... show full transcript
Worked Solution & Example Answer:This question is about Group 1 elements - AQA - GCSE Chemistry - Question 4 - 2021 - Paper 1
Step 1
Give two observations you could make when a small piece of potassium is added to water.
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Answer
Potassium floats on the surface of the water.
Potassium reacts vigorously, producing bubbles of hydrogen gas.
Step 2
Complete the equation for the reaction of potassium with water.
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Answer
The balanced equation for the reaction is:
2K+2H2O→2KOH+H2
Step 3
Explain why the reactivity of elements changes going down Group 1.
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Answer
Reactivity increases going down Group 1.
This is because the outer electron is further from the nucleus, resulting in less attraction between the nucleus and the outer electron. Additionally, there are more electron shells, which provide greater shielding. This makes the atom lose an electron more easily.
Step 4
Draw a dot and cross diagram to show what happens when atoms of sodium and oxygen react to produce sodium oxide.
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Answer
The dot and cross diagram shows the following:
Sodium atom (Na) contributes one electron, becoming a Na^+ ion.
Oxygen atom (O) gains two electrons, becoming an O^2- ion.
Two sodium atoms react with one oxygen atom:
Na• + •Na + •O• → Na^+ + O^2- + Na^+
Step 5
Why is oxygen described as being reduced in the reaction between sodium and oxygen?
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Oxygen is described as being reduced because it gains electrons from sodium during the reaction.
Step 6
Explain why sodium oxide has a high melting point.
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Answer
Sodium oxide has a high melting point due to its giant ionic structure. The strong electrostatic forces of attraction between oppositely charged ions require a large amount of energy to break. Thus, sodium oxide's melting point is significantly high.
