Radioactive Decay

This lesson covers radioactive decay as required by the AQA GCSE Physics specification (4.4.2). You need to understand what radioactive decay is, why it happens, what types of radiation are emitted, and the concept of random and spontaneous decay.

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What Is Radioactive Decay?

Radioactive decay is the process by which an unstable nucleus releases energy by emitting radiation. The nucleus changes to become more stable.

Key characteristics of radioactive decay:

• It is random — you cannot predict when a particular nucleus will decay. Each unstable nucleus has the same chance of decaying in any given time period, but you cannot say exactly when it will happen.
• It is spontaneous — it happens on its own, without any external trigger. It is not affected by temperature, pressure, chemical reactions, or any other physical conditions.
• It involves the nucleus — radioactive decay is a nuclear process, not a chemical one. It occurs because the nucleus is unstable, not because of the electrons.