P7: Radioactivity

When an unstable nucleus will become more stable over time by spontaneously (random) emitting ionising radiation.

Radioactive substances

Alpha Beta Gamma

A type of radiation produced by alpha decay. It releases helium nuclei, known as alpha particles

Another type of radiation produced by beta decay. It releases electrons known as beta particles

Final type of radiation produced by gamma decay. It is a high electromagnetic energy wave with higher frequencies than X Rays

Helium nuclei

Electron

Unpredictable We cannot predict when atoms will emit ionising radiation

Cloud chambers Photographic film Geiger counter

Containers full of air containing alcohol vapour. Ionising radiation enters the air and leaves a trail of ionised air molecules. The alcohol vapour condenses on the ionised air molecules, showing the trail of radiation

Ionising radiation shares the same effect with this and light. A bright spot appears wherever ionising radiation hits the film

Ionising radiation enters a tube of low pressure gas. Atoms in the gas are ionised, knocking electrons out of the atom. Gases then conduct electricity and completes an electric circuit. When radioactive substances enter a Geiger counter, it makes a clicking noise

This is when atoms or isotopes are very common, they even exist in our body. They decay radioactively, meaning we are always surrounded by background radiation

Number of decays recorded per second

Foods Radon gas Rocks Sun

An alpha particle contains 2 protons and 2 neutrons. This creates a relative mass of 4 for an alpha particle. Alpha particles are big and heavy so alpha radiation is strongly ionising. They do lots of damage, but can be stopped by small amounts of matter such as paper

A beta particle is made up of high energy electrons. Beta radiation is more penetrating than gamma radiation but less ionising than alpha radiation. It can pass through paper but is stopped by aluminium foil

Gamma radiation is the least ionising of the three. It does deal less damage than alpha and beta radiation and cannot be stopped by ANYTHING

Strongly ionising radiation is less likely to penetrate materials. It damages materials much more so it comes to a stop soon.

Gamma is the most penetrating Alpha is the most ionising

Paper production Beta particles are able to be chucked through paper to observe whether the paper produced is the right thickness.

Fewer beta particles reach the detector. Production is then stopped

Smoke detectors A radioactive material fires alpha particles at a smoke detector.