Editing Period 6 element (section)

===Barium===
{{main|Barium}}
'''Barium''' is a [[chemical element]] with the symbol '''Ba''' and [[atomic number]] 56. It is the fifth element in Group 2, a soft silvery [[metal]]lic [[alkaline earth metal]]. Barium is never found in nature in its pure form due to its [[Reactivity (chemistry)|reactivity]] with [[Earth's atmosphere|air]]. Its oxide is historically known as [[Barium hydroxide|baryta]] but it reacts with water and carbon dioxide and is not found as a mineral. The most common naturally occurring minerals are the very insoluble barium sulfate, BaSO<sub>4</sub> ([[barite]]), and [[barium carbonate]], BaCO<sub>3</sub>([[witherite]]). Barium's name originates from [[Greek language|Greek]] ''barys'' (βαρύς), meaning "heavy", describing the high density of some common barium-containing ores.

Barium has few industrial applications, but the metal has been historically used to [[getter|scavenge air]] in [[vacuum tube]]s. Barium compounds impart a green color to flames and have been used in fireworks. [[Barium sulfate]] is used for its density, insolubility, and X-ray opacity. It is used as an insoluble heavy additive to oil well drilling mud, and in purer form, as an X-ray [[radiocontrast agent]] for imaging the human gastrointestinal tract. Soluble barium compounds are poisonous due to release of the soluble barium ion, and have been used as rodenticides. New uses for barium continue to be sought. It is a component of some "high temperature" [[YBCO]][[superconductors]], and electroceramics.