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Barium is a chemical element; it has symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal . Because of its high chemical reactivity , barium is never found in nature as a free element.
This is a list of chemical elements and their atomic properties, ordered by atomic number (Z).. Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.
Naturally occurring barium (56 Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks) in 2001. [4]
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Just as atomic units are given in terms of the atomic mass unit (approximately the proton mass), the physically appropriate unit of length here is the Bohr radius, which is the radius of a hydrogen atom. The Bohr radius is consequently known as the "atomic unit of length". It is often denoted by a 0 and is approximately 53 pm. Hence, the values ...
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
Barium is used in vacuum tubes as a getter to remove gases. [61] Barium sulfate has many uses in the petroleum industry, [4] [80] and other industries. [4] [61] [81] Radium has many former applications based on its radioactivity, but its use is no longer common because of the adverse health effects and long half-life.
For stable elements, the formal standard atomic weight (s.a.w.) is added, as published by CIAAW. When the s.a.w. is in interval-notation, its conventional value is added too. Data is retrieved from central s.a.w. values lists, formatting is by {{Infobox element/standard atomic weight format}} (same as {{infobox element}}). Example: