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Radioactivity and Nuclear Decay - SS1 Physics Lesson Note

Radioactivity refers to the spontaneous emission of radiation from unstable atomic nuclei. It occurs when the nucleus of an atom undergoes a nuclear decay process, resulting in the release of radiation. Radioactive decay can be categorised into three main types: alpha decay, beta decay, and gamma decay.

1. Alpha Decay:

-       Alpha decay occurs when an atomic nucleus emits an alpha particle, which consists of two protons and two neutrons (essentially a helium nucleus).

-       During alpha decay, the atomic number decreases by 2, and the mass number decreases by 4.

-       The emission of an alpha particle reduces the overall positive charge of the nucleus, making it more stable.

2. Beta Decay:

-       Beta decay involves the emission of a beta particle from an atomic nucleus.

-       There are two types of beta decay: beta-minus (β-) decay and beta-plus (β+) decay.

-       In beta-minus decay, a neutron in the nucleus is transformed into a proton, and an electron (beta particle) is emitted. The atomic number increases by 1 while the mass number remains the same.

-       In beta-plus decay, a proton in the nucleus is transformed into a neutron, and a positron (positive beta particle) is emitted. The atomic number decreases by 1 while the mass number remains the same.

3. Gamma Decay:

-       Gamma decay involves the emission of gamma radiation, which is a high-energy electromagnetic wave.

-       Unlike alpha and beta decay, gamma decay does not result in a change in the atomic or mass number of the nucleus. Instead, it occurs to release excess energy from an excited nucleus.

-       Gamma radiation has no charge or mass and can penetrate matter

Radioactive decay processes are random and occur at a constant rate, characterised by the half-life, which is the time taken for half of the radioactive nuclei to decay. Radioactive decay plays a crucial role in fields such as nuclear physics, medicine (radiation therapy and imaging), and dating techniques (radiocarbon dating and radioactive dating).

It is important to note that while radioactivity can have harmful effects on living organisms and the environment, it also has various beneficial applications, such as in medical diagnostics and cancer treatment, energy generation (nuclear power), and scientific research. Proper safety precautions and regulations are in place to ensure the safe handling and use of radioactive materials.

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