a) An atom of potassium has atomic number 19 and mass number 39 - Edexcel - GCSE Chemistry - Question 8 - 2020 - Paper 1
Question 8
a) An atom of potassium has atomic number 19 and mass number 39.
(i) Give the electronic configuration of this potassium atom.
(ii) This potassium atom forms the i... show full transcript
Worked Solution & Example Answer:a) An atom of potassium has atomic number 19 and mass number 39 - Edexcel - GCSE Chemistry - Question 8 - 2020 - Paper 1
Step 1
Give the electronic configuration of this potassium atom.
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Answer
The electronic configuration of potassium (atomic number 19) is 2.8.8.1.
Step 2
Which row shows the number of protons and the number of neutrons in this potassium ion, K⁺?
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Answer
The correct row is A, which shows 19 protons and 20 neutrons. The potassium ion K⁺ has lost one electron, but the number of protons and neutrons remains unchanged.
Step 3
Explain, in terms of electrons, why potassium and caesium are in the same group.
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Answer
Potassium and caesium are in the same group because they both have one electron in their outermost shell. This similar electron configuration results in similar chemical properties.
Step 4
Explain, in terms of these forces, why the boiling point of fluorine is low.
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Answer
Fluorine has weak van der Waals forces between its molecules, which are easily overcome by thermal energy. Consequently, its boiling point is low at -188 °C.
Step 5
Complete the balanced equation for this reaction and add the state symbols.
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Answer
The balanced equation is: K(s) + F₂(g) → 2KF(s). Potassium reacts with fluorine to produce solid potassium fluoride.
Step 6
What are the elements in group 1 of the periodic table called?
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The elements in group 1 are called alkali metals.
Step 7
Give, using Figure 14, the boiling point of bromine.
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The boiling point of bromine is approximately 59 °C.
Step 8
State which two elements from Figure 14 are solids at room temperature.
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Answer
The two elements from Figure 14 that are solids at room temperature are bromine and iodine.
