The periodic table
2 marks · EasyAn atom of aluminium has a mass number of 27 and an atomic number of 13.
Calculate the number of neutrons in an aluminium atom.
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14 (±0)
Common mistakes: 27 + 13 = 40; using atomic number instead
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Marking points
M1 · 1 mark · Attempts correct calculation: 27 - 13.
A1 · 1 mark · Correctly gives final answer 14.
Worked solution
So there are 14 neutrons in an aluminium atom.