Isotopes and Nuclear Radiation

Isotopes are different forms of the same element

All atoms of each element have a set number of protons. The number of protons in an atoms is its atomic number
The mass number is the number of protons+neutrons
Isotopes are atoms with same number of protons different number of neutrons
All elements have different isotopes, but there are usually only one or two stable ones
The other unstable isotopes tend to decay into other elements and give out radiation as they try to become more stable. This process is called radioactive decay
Radioactive substances spit out one or more types of ionising radiation from their nucleus-the ones you need to know are alpha, beta and gamma radiation
They can also release neutrons when they decay, as they rebalance their atomic and mass numbers
Ionising radiation is radiation that knocks electrons off atoms, creating positive ions, The ionising power of a radiation source is how easily it can do this

Alpha radiation is when an alpha particle is emitted from the nucleus. A a-particle is two neutrons and two protons
They don’t penetrate very far into materials and are stopped quickly-they can only travel a few cm in air and are absorbed by a sheet of paper
Because of their size they are strongly ionising

A beta particles, is simply a fast-moving electron released by the nucleus. Beta particles have virtually no mass and a charge of -1
They are moderately ionising. They penetrate moderately far into materials before colliding and have a range in air of a few meters. They are absorbed by a sheet of aluminium
For every beta particle emitted, a neutron in the nucleus has turned into a proton

Gamma rays are waves of electromagnetic radiation released by the nucleus
They penetrate far into materials without being stopped and will travel a long distance through air
This means they are weakly ionising because they tend to pass through rather than collide with atoms. Eventually they hit something and do damage
They can be absorbed by thick sheets of lead or metres of concrete

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