Is the process by which a nucleus of an unstable atom loses energy by emitting radiation.
Radioactive decay involves the spontaneous transformation of one element into another. The only way that this can happen is by changing the number of protons in the nucleus (an element is defined by its number of protons). There are a number of ways that this can happen and when it does, the atom is forever changed. Radioactivity and radioactive decay are spontaneous processes. Students often struggle with this concept; therefore, it should be stressed that it is impossible to know exactly when each of the radioactive elements in a rock will decay. Radioactive Decay. Radioactivity is the spontaneous disintegration of atomic nuclei. This phenomenon was first reported in 1896 by the French physicist Henri Becquerel. Marie Curie and her husband Pierre Curie contributed further to the understanding of radioactivity. The process of radioactive decay, can be achieved via three primary methods; a nucleus can change one of its neutrons into a proton with the simultaneous emission of an electron (beta decay), by emitting a helium nucleus (alpha decay), or by spontaneous fission (splitting) into two fragments. Radioactive decay, also known as nuclear decay or radioactivity, is the process by which a nucleus of an unstable atom loses energy by emitting radiation. A material that spontaneously emits such radiation — which includes alpha particles, beta particles, gamma rays and conversion electrons — is considered radioactive. Radioactive decay is a stochastic (i.e. random) process at the level of single atoms, in that, according to quantum theory, it is impossible to predict when a particular atom will decay. From Wikipedia, the free encyclopedia. Spontaneous emission is the process by which a quantum system such as an atom, molecule, nanocrystal or nucleus in an excited state undergoes a transition to a state with a lower energy (e.g., the ground state) and emits quanta of energy.  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. Radioactive decay is a stochastic (i.e. random) process at the level of single atoms, in that, according to quantum theory, it is impossible to predict when a particular atom will decay. Radioactive decay is the spontaneous change or disintegration of an unstable atomic nucleus as it transforms itself to lose energy. When an unstable nucleus of a radioactive isotope spontaneously  decays, the radioactive decay process is normally gamma radiation,  beta particle or alpha particle emission … . During alpha emission, an  alpha particle or Helium-4 is released and the original isotope  becomes another isotope or element Beta decay. Beta decay (β -decay) is the spontaneous inter-conversion of protons and neutrons. It occurs within the nucleus and is accompanied by the emission or absorption of electrons (e –) or positrons (e +) and neutrinos (ve) or antineutrinos (v̄e): (1) Electron β - -decay: n → p β- = e - + v̄e. Spontaneous fission. Spontaneous fission is the spontaneous decay of heavy nuclei into two or, less frequently, three or four fragments, which are the nuclei of elements in the middle of the periodic system. Spontaneous fission and alpha decay limit the possibilities of obtaining new transuranium elements.
http://serc.carleton.edu/quantskills/methods/quantlit/RadDecay.html http://www.atomicarchive.com/Physics/Physics5.shtml https://en.wikipedia.org/wiki/Radioactive_decay https://en.wikipedia.org/wiki/Spontaneous_emission https://en.wikipedia.org/wiki/Radioactive_decay http://www.answers.com/Q/Is_Radioactive_decay_spontaneous http://encyclopedia2.thefreedictionary.com/Radioactivity
what is spontaneous radioactive decay