Standard atomic weight real life substances—for example, in pharmaceuticals and scientific research. Atomic weights are specific to single sources and samples of an element, such as the atomic weight of carbon in a particular bone from a particular archeological site. Standard atomic weight generalizes such values to the "range of atomic weights" which a chemist might expect to derive from many random samples from Earth. This range is the cause of the "interval notation" in some standard atomic weight values. Out of the 118 known chemical elements, 84 are stable and have this Earth-environment based value. Typically, such a value is, for example
Isotopes of nihonium is given. DNS = Di-nuclear system; σ = cross section Isotopes of nihonium Nihonium (Nh) is a synthetic element. Being synthetic, a standard atomic weight cannot be given and like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was Nh as a decay product of Mc in 2003. The first isotope to be directly synthesized was Nh in 2004. There are 6 known radioisotopes from Nh to Nh, along with the unconfirmed Nh. The longest-lived isotope is Nh with a half-life of 8 seconds. Super-heavy elements such as nihonium are produced by bombarding lighter