Answers to AQA GCSE Isotopes

Practice Questions

1. State the definition of an isotope

Isotopes are atoms of the same element, with the same number of protons, but different number of neutrons.

2. State the number of protons, neutrons and electrons in carbon-14

Mass number = 14, atomic number = 6

Protons = 6

Neutrons = 8 (14-6)

Electrons = 6

3. Explain why carbon-13 is not radioactive, but carbon-14 is radioactive

Carbon 13 has the correct ratio of protons to neutrons in the nucleus, but carbon 14 has an incorrect ratio of protons to neutrons in the nucleus, so its nucleus is unstable and will undergo radioactive decay