GCSE Edexcel Chemistry Combined Science States of Matter: This question is about potassium

This question is about potassium and zinc - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2021 - Paper 1

Question 3

This question is about potassium and zinc. (a) Which of the following temperatures is most likely to be the melting point of potassium? ☐ A -63°C ☐ B 6.3°C ☐ C 63°... show full transcript

Worked Solution & Example Answer:This question is about potassium and zinc - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2021 - Paper 1

Step 1

Which of the following temperatures is most likely to be the melting point of potassium?

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Answer

The most likely melting point of potassium is C) 63°C. Potassium is an alkali metal, and alkali metals generally have low melting points. The other options, A, B, and D, do not represent realistic melting points for potassium in its elemental form.

Step 2

Explain how the electronic configuration of an atom of potassium is related to its position in the periodic table.

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Answer

Potassium (K) is situated in group 1 of the periodic table, which consists of alkali metals. Its electronic configuration is

$1s^2 2s^2 2p^6 3s^1$

This configuration indicates that potassium has one electron in its outermost shell (the 3s orbital), making it highly reactive and exhibiting properties typical of alkali metals. Additionally, the position also reflects its reactivity and tendency to lose that single outer electron, leading to the formation of a +1 ion.

Step 3

Describe the test to show that a gas is oxygen.

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Answer

To test for the presence of oxygen gas, introduce a glowing splint into the gas. If oxygen is present, it will relight the glowing splint, indicating the presence of the gas.

Step 4

Write the electronic configurations for the ions in potassium oxide, K₂O.

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Answer

Potassium oxide (K₂O) consists of potassium ions and oxide ions. The electronic configuration for the potassium ion (K⁺) is

$1s^2 2s^2 2p^6 3s^0$

showing it has lost one electron from its outer shell. The electronic configuration for the oxide ion (O²⁻) is

$1s^2 2s^2 2p^6$

indicating it has gained two electrons, filling its outer shell.

This question is about potassium and zinc - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2021 - Paper 1

Worked Solution & Example Answer:This question is about potassium and zinc - Edexcel - GCSE Chemistry Combined Science - Question 3 - 2021 - Paper 1

Which of the following temperatures is most likely to be the melting point of potassium?

Explain how the electronic configuration of an atom of potassium is related to its position in the periodic table.

Describe the test to show that a gas is oxygen.

Write the electronic configurations for the ions in potassium oxide, K₂O.

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