Radionuclides both occur naturally and are artificially made using nuclear reactors, cyclotrons, particle accelerators or radionuclide generators.There are about 650 radionuclides with half-lives longer than 60 minutes (see list of nuclides).Elements heavier than lead, and the elements technetium and promethium, exist only as radionuclides.Founded in 2002 by Nobel Laureate Carl Wieman, the Ph ET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations.Ph ET sims are based on extensive education research and engage students through an intuitive, game-like environment where students learn through exploration and discovery. This excess energy can either create and emit, from the nucleus, new radiation (gamma radiation) or a new particle (alpha particle or beta particle), or transfer this excess energy to one of its electrons, causing it to be ejected (conversion electron).
Most of these are only produced artificially, and have very short half-lives.For comparison, there are about 254 stable nuclides. Even the lightest element, hydrogen, has a well-known radionuclide, tritium.Of these, 34 are primordial radionuclides that existed before the creation of the solar system, and there are another 50 radionuclides detectable in nature as daughters of these, or produced naturally on Earth by cosmic radiation.More than 2400 radionuclides have half-lives less than 60 minutes.Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay.) for that collection can be calculated from their measured decay constants.
The duration of the half-lives of radioactive atoms have no known limits; the time range is over 55 orders of magnitude.