These materials glow in the dark after exposure to light, and he suspected that the glow produced in cathode ray tubes by X-rays might be associated with phosphorescence.He wrapped a photographic plate in black paper and placed various phosphorescent salts on it.
Curie · Skłodowska-Curie · Davisson · Fermi · Hahn · Jensen · Lawrence · Mayer · Meitner · Oliphant · Oppenheimer · Proca · Purcell · Rabi · Rutherford · Soddy · Strassmann · Szilárd · Teller · Thomson · Walton · Wigner Radioactive decay (also known as nuclear decay or radioactivity) is the process by which the nucleus of an unstable atom loses energy by emitting radiation, including alpha particles, beta particles, gamma rays, and conversion electrons.
The transformation produces an atom in a different state (a nucleus containing a different number of protons and neutrons).
Alpha decay is one type of radioactive decay, in which an atomic nucleus emits an alpha particle, and thereby transforms (or "decays") into an atom with a mass number decreased by 4 and atomic number decreased by 2. A decay, or loss of energy from the nucleus, results when an atom with an initial type of nucleus, called the parent radionuclide (or parent radioisotope), transforms into a daughter nuclide.
A radioactive source emits its decay products isotropically (all directions and without bias) There are many different types of radioactive decay.
There exist twenty-nine chemical elements on Earth that are radioactive.
They are those that contain thirty-four radionuclides that date before the time of formation of the solar system, and are known as primordial nuclides.This decay, called spontaneous fission, happens when a large unstable nucleus spontaneously splits into two (and occasionally three) smaller daughter nuclei, and generally leads to the emission of gamma rays, neutrons, or other particles from those products.For a summary table showing the number of stable and radioactive nuclides in each category, see radionuclide.Highly excited neutron-rich nuclei, formed as the product of other types of decay, occasionally lose energy by way of neutron emission, resulting in a change from one isotope to another of the same element..The nucleus may capture an orbiting electron, causing a proton to convert into a neutron in a process called electron capture.These radiations were given the name "Becquerel Rays".