Science / Periodic Table of Elements / Barium (Ba): Atomic number: 56, Atomic mass: 137.33 g.mol -1, Electronegativity: 0.9, Density: 3.5 g.cm-3 at 20°C, Melting point: 725 °C, Boiling point: 1640 °C, Vanderwaals radius: 0.222 nm, Ionic radius: 0.135, Isotopes: 16, Electronic shell: [ Xe ] 6s2, Energy of first ionisation: 502.7 kJ.mol -1, Energy of second ionisation: 965 kJ.mol -1, Standard potential: - 2.90 V, Discovered by: Sir Humphrey Davy in 1808. Barium is a silvery-white metal that can be found in the environment, where it exists naturally. It occurs combined with other chemicals, such as sulfur, carbon or oxygen. Ii is very light and its density is half that of iron. Barium oxidizes in air, reacts vigoroulsy with water to form the hydroxide, liberating hydrogen. Barium reacts with almost all the non-metals, forming often poisouning compounds. Applications: Barium is often used in barium-nickel alloys for spark-plug electrodes an in vacuum tubes as drying and oxygen-removing agent. It is also used in fluorescent lamps: impure barium sulfide phosphoresces after exposure to the light. Barium compounds are used by the oil and gas industries to make drilling mud. Drilling mud simplifies drilling through rocks by lubricating the drill. Barium compounds are also used to make paint, bricks, tiles, glass, and rubber. Barium nitrate and clorate give fireworks a green colour. Barium in the environment: Barium is surprisingly abundant in the Earth's crust, being the 14th most abundant element. High amounts of barium may only be found in soils and in food, such as nuts, seaweed, fish and certain plants. Because of the extensive use of barium in the industries human activities add greatly to the release of barium in the environment. As a result barium concentrations in air, water and soil may be higher than naturally occurring concentrations on many locations. Barium enters the air during mining processes, refining processes, and during the production of barium compounds. It can also enter the air during coal and oil combustion. The chief mined ores are barite, which is also the most common and witserite. The main mining areas are UK, Italy, Czech Republic, USA and Germany. Each year about 6 million tonnes are produced and reserves are expected to exceed 400 million tonnes.
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