Modes of Radioactive Decay

Modes of Radioactive Decay

• Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. This instability stems from an imbalance in the ratio of protons to neutrons in the nucleus.
• Several different modes of radioactive decay exist, each characterized by the type of radiation emitted.
• Common modes of decay include alpha decay, beta decay (both beta-minus and beta-plus), gamma decay, and electron capture.

Alpha Decay

• In alpha decay, an unstable nucleus emits an alpha particle, which is a helium nucleus (2 protons and 2 neutrons).
• This process decreases the atomic number of the nucleus by 2 and the mass number by 4.
• Alpha particles are relatively large and have a relatively short range in matter. They are easily stopped by a sheet of paper.

Beta Decay (Beta-minus)

• Beta-minus decay occurs when a neutron in the nucleus transforms into a proton, an electron (beta particle), and an antineutrino.
• This process increases the atomic number of the nucleus by 1, while the mass number remains the same.
• Beta particles are electrons with a much higher speed and penetrating power than alpha particles. They can penetrate several millimeters of aluminum.

Beta Decay (Beta-plus)

• In beta-plus decay, a proton transforms into a neutron, a positron (a positively charged electron), and a neutrino.
• This process decreases the atomic number of the nucleus by 1, while the mass number remains the same.
• Positrons have the same mass and opposite charge to electrons and, when they encounter electrons, annihilate each other, releasing energy in gamma rays.

Gamma Decay

• Gamma decay is a type of electromagnetic radiation, and is not a change in the number of protons or neutrons.
• It occurs when a nucleus is in an excited state and releases energy (gamma rays) as it transitions to a lower energy state.
• Gamma rays have high energy and can penetrate through significant thicknesses of material. Lead shielding is often used to block gamma radiation.

Electron Capture

• Electron capture is a process that is similar to beta-plus decay.
• It occurs when a nucleus captures one of the inner orbital electrons, effectively converting a proton into a neutron and releasing a neutrino.
• This process decreases the atomic number by 1 without changing the mass number.

Alpha Particle

• An alpha particle is a helium nucleus consisting of two protons and two neutrons.
• It carries a positive charge of +2.
• Alpha particles have a relatively low penetration power.

Beta Particle

• A beta particle can be either an electron or a positron.
• An electron is negatively charged (-1) and a positron is positively charged (+1).
• Beta particles have a higher penetration power comparatively to alpha particles.