What is Barium?
{{infobox barium}} [[File:Barium 1.jpg|thumb|Corroded barium metal]] '''Barium''' is [[chemical element]] 56 on the [[periodic table]]. Its symbol is '''Ba'''. It contains 56 [[proton]]s and 56 [[electron]]s. Its mass number is about 137.3. It is a [[metal]]. ==Properties== ===Physical properties=== Barium is part of a group of elements known as the [[alkaline earth metal]]s. It is a silvery metal that easily turns black. It is soft and [[wikt:ductile|ductile]]. It can form [[alloy]]s with some metals that are partially alloys and partially [[chemical compound]]s. ===Chemical properties=== Barium is reactive, and if you put pure barium metal in the air, it will react with [[oxygen]]. At first it will turn black, then white as [[barium oxide]] is formed. Barium reacts with water to make [[barium hydroxide]] and [[hydrogen gas]]. Barium also reacts very fast with [[acid]]s to make a barium salt and hydrogen. Barium can form [[barium peroxide]] if it is burned in air. Barium reacts with many other metal oxides and sulfides to make barium oxide or sulfide and the metal. It also reacts with carbon and nitrogen at a high temperature to make barium cyanide. ===Chemical compounds=== {{See also cat|Barium compounds}} Barium is too reactive as a metal, so it is not found in the earth as a metal. It is found in chemical compounds. Barium only occurs in one [[oxidation state]]: +2. Most barium compounds are colorless. The ones that dissolve in water or stomach acid are very toxic. [[Barium sulfate]] is well known because it does not dissolve in water or acids. Barium compounds are quite heavy. Barium compounds put out a greenish flame when heated red-hot. <gallery> File:Barium chloride dihydrate.jpg|Barium chloride File:Bariumsulfatpulver.png|Barium sulfate </gallery> ==Occurrence== [[File:Barite.jpg|thumb|Barium sulfate as barite]] Barium is found as [[barium sulfate]] (barite) and [[barium carbonate]] (witherite) in the ground. Both of these [[mineral]]s do not dissolve in water. Barium sulfate hardly dissolves in