One isotope of the element potassium is potassium-40 - Edexcel - GCSE Physics - Question 4 - 2015 - Paper 1
Question 4
One isotope of the element potassium is potassium-40.
A nucleus of potassium-40 is represented by
$$^{40}_{19}K$$
(i) Complete the sentence by putting a cross (X)... show full transcript
Worked Solution & Example Answer:One isotope of the element potassium is potassium-40 - Edexcel - GCSE Physics - Question 4 - 2015 - Paper 1
Step 1
Complete the sentence by putting a cross (X) in the box next to your answer.
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Answer
The number of neutrons in a nucleus of potassium-40 is 21. This can be calculated by subtracting the atomic number (19) from the mass number (40):
40−19=21
Step 2
Which of these symbols is correct for the nucleus of a different isotope of potassium?
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Answer
The correct symbol for a different isotope of potassium is 2040K. This indicates an isotope with more neutrons than protons.
Step 3
Describe what information this gives about the isotope potassium-40.
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Answer
Potassium-40 is radioactive and undergoes a decay process that emits gamma radiation. This implies that potassium-40 is unstable and transforms into argon-40 while releasing radiation. The fact that argon-40 nuclei never change indicates that they are stable compared to the radioactive nature of potassium-40.
