Isotopes of barium Isotopes of barium Naturally occurring barium (Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, recently identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks). This nuclide decays by double-electron capture (absorbing two electrons and emitting two neutrinos); with a half-life of (0.5–2.7)×10 years (about 10 times the age of the universe). There are a total of thirty-three known radioisotopes in addition to Ba, but most of these are highly radioactive with half-lives in the several millisecond to several minute range. The only notable
Chemical element of whether or not they are ionized or chemically bonded, e.g. hydrogen in water) as well as for a pure chemical substance consisting of a single element (e.g. hydrogen gas). For the second meaning, the terms "elementary substance" and "simple substance" have been suggested, but they have not gained much acceptance in English chemical literature, whereas in some other languages their equivalent is widely used (e.g. French ', Russian '). A single element can form multiple substances differing in their structure; they are called allotropes of the element. When different elements are chemically combined, with the atoms held together by