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Barium Facts

Chemical & Physical Properties

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This is a photo of barium. Barium is a soft silvery-white metal, but it oxidizes very easily in air.

This is a photo of barium. Barium is a soft silvery-white metal, but it oxidizes very easily in air.

Matthias Zepper, public domain This is the electron configuration of a barium atom.

This is the electron configuration of a barium atom.

This is barium on the periodic table.

This is barium on the periodic table.

Todd Helmenstine
Periodic Table of the Elements

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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