Barium
Atomic Number: 56
Symbol: Ba
Atomic Weight: 137.327
Discovery: Sir Humphrey Davy 1808 (England)
Electron Configuration: [Xe] 6s2
Word Origin: Greek barys, heavy or dense
Isotopes: Natural barium is a mixture of seven stable isotopes. Thirteen radioactive isotopes are known to exist.
Properties: Barium has a melting point of 725°C, boiling point of 1640°C, specific gravity of 3.5 (20°C), with a valence of 2. Barium is a soft metallic element. In its pure form, it is silvery white. The metal oxidizes readily and should be stored under petroleum or other oxygen-free liquids. Barium decomposes in water or alcohol. Impure barium sulfide phosphoresces following exposure to light. All barium compounds that are soluble in water or acid are poisonous.
Uses: Barium is used as a 'getter' in vacuum tubes. Its compounds are used in pigments, paints, glassmaking, as weighting compounds, in the manufacture of rubber, in rat poison, and in pyrotechnics.
Sources: Barium is only found combined with other elements, primarily in barite or heavy spar (sulfate) and witherite (carbonate). The element is prepared by the electrolysis of its chloride.
Element Classification: Alkaline-earth Metal
Density (g/cc): 3.5
Melting Point (K): 1002
Boiling Point (K): 1910
Appearance: soft, slightly malleable, silver-white metal
Atomic Radius (pm): 222
Atomic Volume (cc/mol): 39.0
Covalent Radius (pm): 198
Ionic Radius: 134 (+2e)
Specific Heat (@20°C J/g mol): 0.192
Fusion Heat (kJ/mol): 7.66
Evaporation Heat (kJ/mol): 142.0
Pauling Negativity Number: 0.89
First Ionizing Energy (kJ/mol): 502.5
Oxidation States: 2
Lattice Structure: Body-Centered Cubic
Lattice Constant (Å): 5.020
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)
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