radyoaktif

Radyoaktif describes substances that emit radiation due to unstable atomic nuclei. The phenomenon, known as radioactivity, was first observed by Henri Becquerel in 1896 and later studied in depth by Marie and Pierre Curie. Radyoaktif materials occur naturally, such as uranium, thorium, and potassium-40, and can also be produced or prepared for specific uses in medicine, industry, and energy.

Radioactivity involves the emission of ionizing radiation in several forms. Alpha particles are heavy and carry a positive charge; beta particles are electrons or positrons; gamma rays are high‑energy photons; neutrons are uncharged particles that can be liberated in certain reactions. The nucleus may decay by alpha, beta, or gamma processes, sometimes accompanied by neutron emission. Different isotopes have characteristic half-lives, ranging from fractions of a second to millions of years, which governs their activity and handling requirements.

Measurement and safety: the activity of a radioactive source is expressed in becquerels, representing decays per second, while absorbed dose is measured in grays and biological effect in sieverts. The concept of half-life describes how long it takes for activity to halve. Radiological protection follows the ALARA principle—keeping exposure as low as reasonably achievable—and relies on time, distance, and shielding to minimize dose.

Applications and regulation: radyoaktif materials are essential in medicine (diagnostic imaging with radiopharmaceuticals, cancer therapy), industry (nondestructive testing, material sterilization), and energy (nuclear reactors). Regulation ensures safe handling, transport, storage, and disposal of radioactive waste. Environmental and safety concerns include contamination, accidents, and the long-term management of radioactive waste.