Relative atomic mass: 137.327 +- 0.007

English: Barium
French: Baryum
Croatian: Barij
German: Barium
Italian: Bario
Spanish: Bario

Atomic number: 56
Group numbers: 2
Period: 6
Standard state (20 oC): solid

Discovery: 1808 Sir Humphry Davy (GB)
Barium was discovered by Sir Humphry Davy (GB) in 1808. The origin of the name comes from the Greek word barys meaning heavy. It is a soft, slightly malleable, silvery-white metal. Barium oxidises in air and reacts with water. Soluble compounds are toxic by ingestion. Barium is found in barytine (BaSO4) and witherite (BaCO3), it is never found in pure form due to its reactivity. Barium must be stored under kerosene to remain pure. Barite, or barium sulfate (BaSO4) is used as a filter for rubber, plastics and resins. It is insoluble in water and so is used in X-rays of the digestive system. Barium nitrate, Ba(NO3)2, burns brilliant green and is used in fireworks. The price of 99.2 % pure barium pieces is 1347.20 for 1000 g.
Electronic configuration: [Xe] 6s2
Formal oxidation number: +2
Atomic radius: 217.4 pm

Electronegativities: 0.89
Thermal conductivity: 18.4 W/(m K)
Electrical resistivity (20 oC): 50 microOhm cm

Melting point: 727 oC
Boiling point: 1897 oC

Heat of fusion: 7.66 kJ/mol
Heat of vaporization: 150.9 kJ/mol
Heat of atomization: 180.7 kJ/mol

55Cs <= 56Ba => 57La

ASCII Periodic Table of the Elements
29 Aug. 2017
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