How It Works: Why Some Nuclei Are Unstable
Part of Atomic Structure — GCSE Physics
This how it works covers How It Works: Why Some Nuclei Are Unstable within Atomic Structure for GCSE Physics. Revise Atomic Structure in Atomic Structure for GCSE Physics with 13 exam-style questions and 25 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 12 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 6 of 12
Practice
13 questions
Recall
25 flashcards
⚙️ How It Works: Why Some Nuclei Are Unstable
The nucleus is held together by the strong nuclear force — a force that acts between protons and neutrons at extremely short range. This force is much stronger than the electromagnetic repulsion between protons, but it only operates over very short distances.
When the ratio of neutrons to protons is wrong — too many or too few neutrons — the nucleus becomes unstable. An unstable nucleus will spontaneously emit radiation to achieve a more stable configuration. This is the basis of all radioactivity.
Small nuclei (up to calcium) are most stable with roughly equal numbers of protons and neutrons. Large nuclei need more neutrons than protons to provide enough binding force to overcome the greater electrostatic repulsion between many protons.