Types of decay | Nuclear chemistry | Chemistry | Khan Academy

Recent questions

• What is alpha decay in simple terms?

  Alpha decay is a process where an unstable atomic nucleus emits an alpha particle, which consists of two protons and two neutrons. This emission results in a decrease of the atomic mass number by four and the atomic number by two, effectively transforming the original element into a new one. For instance, when uranium-238 undergoes alpha decay, it releases an alpha particle and becomes thorium-234. This process not only changes the identity of the element but also illustrates the fundamental nature of nuclear stability and the mechanisms that lead to the transformation of elements in the periodic table.

• How does beta decay occur?

  Beta decay occurs when a neutron in an atomic nucleus transforms into a proton, resulting in the emission of an electron, known as a beta particle. This transformation increases the atomic number by one while keeping the mass number unchanged, thus creating a new element. For example, iodine, which has 53 protons, can undergo beta decay to become an isotope with 54 protons by converting one of its neutrons into a proton. The emitted beta particle carries away the negative charge, allowing the new isotope to stabilize by acquiring electrons from its surroundings, ultimately returning to a neutral state.

• What is gamma decay?

  Gamma decay is a nuclear process where an unstable nucleus releases energy in the form of gamma rays without changing the number of protons or neutrons within the nucleus. This release of high-energy radiation occurs as particles within the nucleus reconfigure themselves to reach a more stable state. Unlike alpha and beta decay, gamma decay does not result in the transformation of one element into another; instead, it is a way for the nucleus to shed excess energy. Gamma rays are highly penetrating and can pose significant hazards to living organisms, making understanding this decay process crucial in fields such as nuclear physics and radiation safety.

• What happens during positron emission?

  During positron emission, a proton in the nucleus of an atom is converted into a neutron, resulting in the emission of a positron, which is a particle with the same mass as an electron but with a positive charge. This process decreases the atomic number by one while keeping the mass number unchanged, thus forming a new element. For example, when beryllium-7 undergoes positron emission, it transforms into lithium-7. The emitted positron quickly interacts with electrons in the environment, leading to annihilation events that produce gamma radiation, highlighting the intricate balance of particle interactions in atomic decay processes.

• How does alpha decay affect atomic structure?

  Alpha decay significantly alters the atomic structure of an element by reducing both its atomic mass and atomic number. When an unstable nucleus emits an alpha particle, which is essentially a helium nucleus composed of two protons and two neutrons, the original element loses four units of mass and two units of atomic number. This transformation results in the formation of a new element. For instance, uranium-238, upon undergoing alpha decay, becomes thorium-234. The loss of protons and neutrons not only changes the identity of the element but also impacts its chemical properties and stability, illustrating the dynamic nature of atomic interactions and decay processes in nuclear chemistry.