Barium Chemical & Physical Properties

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, a boiling point of 1640°C, and a 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.)