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When isotopes of elements (atoms of the same element with different neutron numbers) have very imbalanced nuceli, meaning there is a large difference between their protons and neutrons, excess energy is given off as radiation. For example, a carbon atom usually has 6 neutrons but it has isotopes with 7 and 8 neutrons. The carbon atom with 8 neutrons is a radioactive element because there is too much energy.
Alpha, Beta and Gamma rays are all different types of radiation emitted from such radioactive isotopes.
- Demonstrate understanding of background radiation.
Radiation is the emission of energy as electromagnetic waves or as moving subatomic particles. Background radiation comes from natural sources such as cosmic rays from space, air, food, radioactive rocks and living things that have absorbed radioactive materials.
- Describe the detection of α-particles, β-particles and γ-rays
We can use the Geiger-Miller counter to detect radioactivity. The counter will click each time a particle of radiation from a radioactive substance enters the tube.
Another method of detection is to use photographic film which darkens when it absorbs radiation.
The picture on the left is that of a film badge where a piece of thin film is kept protected from light exposure. After exposed to radiation it is taken out and developed to measure the exposure.
Notes submitted by Lintha
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IGCSE AID 