Radioactive decay for SQA Higher Physics

A nucleus is said to be stable if it has a certain amount of neutrons depending on the number of protons it has. If there are too many or too few neutrons, the nucleus is said to be unstable and will decay by emitting radiation. The same number of protons and neutrons are needed for nuclei of elements of fewer protons to be stable. The greater the number of protons, the more neutrons are needed for the nucleus to be stable. Radioactive decay occurs randomly and each decay is independent of the rest, therefore predictions about when an atom will decay cannot be made.

1

Explain the state in which a nucleus will decay.

A nucleus will decay when it is unstable. This happens when there are too many or too few neutrons in the nucleus in comparison to the number of protons.

2

Explain the condition that must hold for a nucleus to be stable.

A nucleus is said to be stable if it has a certain amount of neutrons depending on the number of protons it has.

3

Why does a Carbon nucleus require less neutrons than a Mercury one to be stable?

Mercury nuclei have a greater number of protons than Carbon ones, therefore they require a greater number of neutrons to be stable.

4

Explain how each decay of a radioactive sample is related to the rest of the decays.

Radioactive decay occurs randomly and each decay is independent, therefore the decays of a radioactive sample are not related to each other.

5

How does an unstable nucleus become stable?

Unstable nuclei will decay since they are unstable to get to a stable state. This is done by emitting radiation.

End of page