Period 6 element years and is used in medical applications, industrial gauges, and hydrology. Although the element is only mildly toxic, it is a hazardous material as a metal and its radioisotopes present a high health risk in case of radioactivity releases. Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with water and carbon dioxide and is
Monoisotopic element primordially which are not monoisotopic because the naturally occurring nuclide is radioactive, and thus the element has no stable isotopes at all. For an element to be monoisotopic, it must have one stable nuclide. Non-mononuclidic elements are marked with an asterisk, and the long-lived primordial radioisotope given. In two notable cases (indium and rhenium), the highest abundance naturally occurring isotope is the mildly radioactive one, and in the case of europium, nearly half of it is. Monoisotopic element A monoisotopic element is one of 26 chemical elements which have only a single stable isotope (nuclide). A list is given in