Decay, radioactive

Radioactive Decay

Radioactive decay is a fundamental process in nuclear physics and chemistry, where an unstable atomic nucleus loses energy by emitting radiation. This process is a random and spontaneous event that results in the transformation of an unstable isotope into a more stable one, often of a different element. Radioactive decay is a key concept in understanding nuclear reactions, nuclear energy, and the natural radioactivity found in the environment.

Types of Radioactive Decay

Radioactive decay can occur through several different processes, each characterized by the type of radiation emitted and the changes in the nucleus:

Alpha Decay

Alpha decay involves the emission of an alpha particle, which consists of two protons and two neutrons (essentially a helium-4 nucleus). This type of decay typically occurs in heavy elements, such as uranium and radium. The emission of an alpha particle results in a decrease in the atomic number by 2 and the mass number by 4.

Beta Decay

Beta decay is a process where a beta particle (an electron or a positron) is emitted from the nucleus. There are two types of beta decay:

• Beta-minus decay (β⁻ decay):A neutron is converted into a proton, and an electron and an antineutrino are emitted. This increases the atomic number by 1.
• Beta-plus decay (β⁺ decay):A proton is converted into a neutron, and a positron and a neutrino are emitted. This decreases the atomic number by 1.

Gamma Decay

Gamma decay involves the emission of gamma rays, which are high-energy photons. This type of decay usually follows alpha or beta decay, as the nucleus transitions from a higher energy state to a lower energy state without a change in the number of protons or neutrons.

Other Types of Decay

Other less common types of radioactive decay include:

• Electron capture:An inner orbital electron is captured by the nucleus, converting a proton into a neutron and emitting a neutrino.
• Spontaneous fission:The nucleus splits into two or more smaller nuclei, along with the emission of neutrons and a large amount of energy.

Half-life

The half-life of a radioactive isotope is the time required for half of the radioactive nuclei in a sample to decay. It is a characteristic property of each radioactive isotope and can range from fractions of a second to billions of years. The concept of half-life is crucial in applications such as radiometric dating, nuclear medicine, and nuclear power generation.

Applications of Radioactive Decay

Radioactive decay has numerous applications across various fields:

• Radiometric dating:Techniques such as carbon dating use the known half-lives of isotopes to determine the age of archaeological and geological samples.
• Nuclear medicine:Radioisotopes are used in diagnostic imaging and treatment, such as in PET scans and cancer radiotherapy.
• Nuclear power:The energy released from radioactive decay is harnessed in nuclear reactors to generate electricity.

Safety and Environmental Impact

Radioactive decay can pose significant health and environmental risks due to the ionizing radiation emitted. Proper safety measures, such as shielding and containment, are essential to protect humans and the environment from harmful exposure.

Also see

• Nuclear physics
• Isotope
• Radiometric dating
• Nuclear medicine
• Nuclear power