TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Physics > Radioactivity, half life e.t.c
Alpha particles
- consists of 2 protons and 2 neutrons (Helium nucleus)
- highly ionizing therefore they strongly attract electrons
- have a charge of +1
- bent by electric and magnetic fields but not as much as beta due to larger mass
- relatively heavy and slow moving
- absorbed by skin / 5cm air / card therefore it has poor penetrating power
Beta Particles
- a fast moving electron
- in beta radiation, a neutron turns into a proton and an electron and the electron is ejected
- very light (little mass)
- weak ionizing ability
- move at 9/10 the speed of light
- bent strongly by electric and magnetic fields
- fast moving, moves up to 30-50cm in air, absorbed by 5mm Al. Can ionize an air molecule
Gamma Rays
- electromagnetic rays
- moves at the speed of light
- high energy radiation with shorter wavelength than X rays
- never fully absorbed therefore has a very long range
- very very weakly ionizing because it has no charge or mass
- not affected by electric and magnetic fields
- kills living cells
- only emitted with alpha and beta particles
- strength halved by thick concrete, thick lead (25mm)
==For nuclear equations
- When alpha decay occurs, mass no. decreases by 4 and atomic no. decreases by 2.
- For beta decay, mass number does not change, atomic number increases by 1.
- Gamma decay, a gamma ray is released (energy), no change to mass & atomic number.
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