Physics Form 5: Chapter 5 - Radioactive Decay

Radioactive decay is the breaking up of unstable nuclei into more stable nuclei with the emission of radioactive rays.

There are three main types of radiation:

• Alpha decay
• Beta decay
• Gamma decay

A) Alpha decay

The reason alpha decay occurs is because the nucleus has too many protons which cause excessive repulsion. In an attempt to reduce the repulsion, a Helium nucleus is emitted. The way it works is that the Helium nuclei are in constant collision with the walls of the nucleus and because of its energy and mass, there exists a nonzero probability of transmission. That is, an alpha particle (Helium nucleus) will tunnel out of the nucleus

 

B) Beta decay

Beta decay occurs when the neutron to proton ratio is too great in the nucleus and causes instability. In basic beta decay, a neutron is turned into a proton and an electron. The electron is then emitted

C) Gamma decay

Gamma decay occurs because the nucleus is at too high an energy. The nucleus falls down to a lower energy state and, in the process, emits a high energy photon known as a gamma particle.