P7 Radioactivity - The Basics
Radioactive decay is simply when an unstable atomic nucleus becomes stable by chucking out nuclear radiation. Think of it like a wobbly chair finally settling down, but instead of creaking, it releases energy and particles.
Isotopes are versions of the same element that have identical numbers of protons but different numbers of neutrons. It's like having the same car model but with different engine sizes - they're fundamentally the same but behave differently.
There are four main types of nuclear radiation you need to know. Alpha particles contain 2 protons and 2 neutrons (mass number 4), making them quite chunky. Beta particles are high-speed electrons created when a neutron transforms into a proton inside the nucleus. Gamma rays are electromagnetic waves with very high frequency and short wavelengths. Finally, neutrons are uncharged particles that can also be emitted.
💡 Quick Tip: Remember that radioactive decay is the nucleus trying to become more stable - it's nature's way of finding balance!
The penetrating power and range of these radiations vary massively. Alpha particles only travel a few centimetres in air and can be stopped by thin paper, but they're strongly ionising. Beta particles can travel several metres and are moderately penetrating and ionising. Gamma rays can travel enormous distances, penetrate most materials, but are only weakly ionising.
Half-life describes how predictable radioactive decay is with large numbers of nuclei. Although you can't predict which individual nucleus will decay next (it's completely random), scientists can accurately predict how long it takes for half of a large sample to decay.
