Radioaktivnost

Radioaktivnost, also known as radioactivity, is a property exhibited by certain types of matter of emitting radiation and energetic particles spontaneously. This phenomenon was first observed by Henri Becquerel in 1896, who discovered that uranium salts emitted invisible rays that could darken a photographic plate. The term "radioactivity" was coined by Marie Curie, who, along with her husband Pierre, conducted extensive research on the subject.

Radioactive decay is the process by which an unstable atomic nucleus loses energy by emitting radiation. This can occur through several mechanisms, including alpha decay, beta decay, and gamma decay. Alpha decay involves the emission of an alpha particle, which is a helium-4 nucleus. Beta decay, on the other hand, involves the emission of electrons or positrons. Gamma decay, the most energetic of the three, involves the emission of gamma rays, which are high-energy photons.

Radioactive materials are used in various applications, including medicine, industry, and research. In medicine, radioactive isotopes are used for diagnostic imaging and cancer treatment. In industry, they are used for sterilization and material analysis. However, radioactivity also poses significant health risks, as exposure to radiation can cause cellular damage, leading to conditions such as cancer and radiation sickness.

The International System of Units (SI) defines the unit of radioactivity as the becquerel (Bq), which is equal to one decay per second. Another commonly used unit is the curie (Ci), which is equal to 3.7 x 10^10 decays per second. The half-life of a radioactive isotope is the time required for the quantity of the isotope to reduce to half its initial value, a property that is unique to each isotope.