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.
It produces a lilac flame and effervescence, indicating rapid chemical reaction.
Step 2
Complete the equation for the reaction of potassium with water.
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Answer
K + 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 the group because the outer electron is further from the nucleus. As more shells are added, the atom becomes larger, leading to less attraction between the nucleus and the outer electron. Consequently, the atom loses 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 reaction can be represented as follows:
Sodium atoms lose one electron each, while oxygen gains two electrons.
The dot and cross diagram shows sodium ions (Na+) with a positive charge and an oxide ion (O2-) with a negative charge:
Sodium Ion: Na+
Oxide Ion: O2-
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 the sodium atoms during the formation of sodium oxide.
Step 6
Explain why sodium oxide has a high melting point.
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Answer
Sodium oxide forms a giant ionic lattice structure with strong electrostatic forces of attraction between the oppositely charged ions. As a result, large amounts of energy are required to break these bonds, leading to a high melting point.
