# Radioactive Decay and Its Types Radioactive decay is a process by which unstable atomic nuclei lose energy by emitting radiation. The main types of decay relevant to genetic damage are alpha, beta, and gamma decay. --- ## 1) What is Radioactive Alpha Decay? **Alpha decay** is a type of radioactive decay in which an unstable nucleus emits an alpha particle. - **Alpha particle:** Consists of 2 protons and 2 neutrons (identical to the nucleus of a helium atom). - **Result:** The original atom loses 2 protons and 2 neutrons, forming a new element with a lower atomic number and mass. - **Example:** \[ {}^{238}_{92}\text{U} \rightarrow {}^{234}_{90}\text{Th} + {}^{4}_{2}\text{He} \] - **Penetration:** Alpha particles have low penetration and can be stopped by a sheet of paper or skin, but are highly damaging if ingested or inhaled. --- ## 2) What is Radioactive Beta Decay? **Beta decay** is a process in which a radioactive nucleus emits a beta particle, which can be an electron or a positron. - **Types:** - **Beta-minus (β⁻) decay:** A neutron turns into a proton, emitting an electron and an antineutrino. \[ n \rightarrow p^+ + e^- + \bar{\nu}_e \] - **Beta-plus (β⁺) decay:** A proton turns into a neutron, emitting a positron and a neutrino. \[ p^+ \rightarrow n + e^+ + \nu_e \] - **Result:** The atomic number changes by one, altering the element. - **Penetration:** Beta particles penetrate further than alpha particles, but can be stopped by plastic or glass. --- ## 3) What is a Gamma Ray? **Gamma rays** are a form of electromagnetic radiation (high-energy photons) emitted by atomic nuclei. - **Emission:** Often occurs after alpha or beta decay, when the nucleus transitions from a high-energy state to a lower-energy state. - **Properties:** - No mass and no charge. - Extremely high energy and deep penetration—can pass through the human body and require dense materials like lead for shielding. - **Effect:** Gamma rays can ionize atoms and damage DNA, increasing the risk of mutations and cancer. --- ## Summary Table | Decay Type | Emitted Particle | Atomic Change | Penetration | Genetic Risk | |------------|------------------|--------------|-------------|--------------| | Alpha | \( ^4_2He \) | -2p, -2n | Low | High (if internal) | | Beta | \( e^- \) or \( e^+ \) | ±1p, ∓1n | Moderate | Moderate | | Gamma | Photon (\( \gamma \)) | None (energy loss) | High | High | --- **Image Suggestion:** *Diagram showing alpha, beta, and gamma radiation paths through matter—illustrating different penetration levels and shielding materials.* *Alt text: Diagram comparing the penetration of alpha, beta, and gamma radiation through paper, aluminum, and lead.*