Alpha, beta, and gamma radiations are the three main types of nuclear radiation released during radioactive decay. These emissions help unstable nuclei become more stable. Understanding the differences between them is essential for IB Chemistry Topic 12 (Atomic Structure), particularly when studying nuclear equations, half-life, and radioactivity. Each type of radiation has unique characteristics, penetration abilities, and effects on matter.
What Is Nuclear Radiation?
When an unstable nucleus undergoes radioactive decay, it emits particles or energy. These emissions fall into three categories:
- Alpha particles (α)
- Beta particles (β⁻ or β⁺)
- Gamma rays (γ)
They differ in mass, charge, penetration power, and ionizing ability. These differences explain why they behave differently in electric fields, matter, and living tissues.
1. Alpha Radiation (α)
What is an alpha particle?
An alpha particle is a helium nucleus:
- 2 protons
- 2 neutrons
- Charge: +2
- Mass: 4 atomic mass units
Symbol: ⁴₂He or α
Key properties
- Heavy and slow-moving
- Highly ionizing (causes strong damage to cells)
- Low penetrating power: stopped by paper or human skin
- Travel only a few centimeters in air
When does alpha decay occur?
Alpha emission happens in very heavy, unstable nuclei such as:
