Barium Facts - Periodic Table of the Elements

Barium Facts - Periodic Table of the Elements 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 725Â °C, a boiling point of 1640Â °C, and a specific gravity of 3.5 (20Â °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 (20Â °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 (Ã…) 5.020 References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Langes Handbook of Chemistry (1952), CRC Handbook of Chemistry Physics (18th Ed.)