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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?
Answer
The melting point of potassium is most likely to be 63°C (C). This is because potassium is an alkali metal, which typically have low melting points. Among the given options, -63°C would make potassium a gas at room temperature, while 6.3°C and 630°C are not representative of potassium's melting point.
Step 2
Explain how the electronic configuration of an atom of potassium is related to its position in the periodic table.
Answer
Potassium (K) has the atomic number 19, which means it has 19 electrons. Its electronic configuration is 1s² 2s² 2p⁶ 3s¹. Potassium is located in Group 1 of the periodic table, which consists of alkali metals. The single electron in the outermost shell (3s¹) determines its chemical reactivity and its position. As you move down Group 1, the reactivity increases due to the increasing atomic size and decreasing ionization energy.
Step 3
Step 4
Write the electronic configurations for the ions in potassium oxide, K₂O.
Answer
In potassium oxide (K₂O), potassium forms K⁺ ions. The electronic configuration for K⁺ is 1s² 2s² 2p⁶. Oxygen (O) in K₂O forms O²⁻ ions, and its electronic configuration is 1s² 2s² 2p⁶ 3s² 3p⁴. When it gains two electrons to achieve its stable electronic configuration, it becomes O²⁻ with the configuration 1s² 2s² 2p⁶.