THE STABILITY OF ISOTOPES
2 marks · NormalExplain how the presence of neutrons in the nucleus prevents the protons from repelling and breaking apart the nucleus.
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Neutrons provide the strong nuclear force that binds protons together, overcoming their electrical repulsion and keeping the nucleus stable.
Also accept: Neutrons help balance forces in the nucleus and hold it together.
Common mistakes: Saying neutrons are not involved in binding; Mixing up nuclear force and electrical force
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Marking points
B1 · 1 mark · Mentions strong nuclear force.
B2 · 1 mark · Explains that this force balances out repulsion between protons.
Worked solution
Neutrons, along with protons, participate in the strong nuclear force, which is much stronger than the electrical repulsion between protons, keeping them together in the nucleus.