Overview
This lecture explains the four types of nuclear radiation—alpha particles, beta particles, gamma rays, and neutrons—including their composition, penetration ability, and ionizing power.
Isotopes and Radioactivity
- Each element exists as isotopes, which are atoms with the same number of protons but different numbers of neutrons.
- Most elements have only one or two stable isotopes; the remaining isotopes are unstable and radioactive.
- Radioactive decay occurs when unstable isotopes emit particles or energy to become more stable.
Types of Nuclear Radiation
Alpha Particles
- Alpha particles consist of two protons and two neutrons (identical to a helium nucleus).
- They have a +2 charge and no electrons.
- Alpha particles have low penetration (stopped by paper) but high ionizing power.
Beta Particles
- Beta particles are high-speed electrons with a -1 charge and very little mass.
- Produced when a neutron turns into a proton and emits an electron.
- Beta particles have moderate penetration (stopped by 5 mm of aluminum) and are moderately ionizing.
Gamma Rays
- Gamma rays are waves of electromagnetic radiation with no mass or charge.
- Often emitted after alpha or beta decay to remove excess energy from the nucleus.
- Gamma rays are weakly ionizing but highly penetrating (stopped by thick lead or meters of concrete).
Neutron Emission
- Unstable nuclei with excess neutrons can emit a neutron to increase stability.
- Less detail was given, but it's another form of nuclear radiation.
Key Terms & Definitions
- Isotope — atoms of the same element with different numbers of neutrons.
- Radioactive Decay — process where unstable nuclei emit particles or energy to become stable.
- Ionizing Power — the ability of radiation to remove electrons from atoms.
- Penetration — how far radiation can travel through materials.
- Alpha Particle — two protons and two neutrons, highly ionizing, low penetration.
- Beta Particle — high-speed electron, moderate ionizing and penetration ability.
- Gamma Ray — electromagnetic radiation, weakly ionizing, highly penetrating.
Action Items / Next Steps
- Review the differences between alpha, beta, gamma, and neutron radiation, focusing on their composition, ionizing power, and penetration ability.