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Cesium Facts

Cesium Chemical & Physical Properties


Cesium is a soft silvery-gold metal.

Cesium is a soft silvery-gold metal with a melting point of 28°C (83°F). The element is shown here in liquid form.

Justin Urgitis, wikipedia.org This is a high-purity sample of cesium crystals.

This is a high-purity sample of cesium crystals maintaining in an ampule under an argon atmosphere.

Dnn87, Wikipedia Commons This is cesium on the periodic table.

This is cesium on the periodic table.

Todd Helmenstine


Atomic Number: 55

Symbol: Cs

Atomic Weight: 132.90543

Element Classification: Alkali Metal

Discoverer: Gustov Kirchoff, Robert Bunsen

Discovery Date: 1860 (Germany)

Name Origin: Latin: coesius (sky blue); named for the blue lines of its spectrum

Density (g/cc): 1.873

Melting Point (K): 301.6

Boiling Point (K): 951.6

Appearance: extremely soft, ductile, light gray metal

Atomic Radius (pm): 267

Atomic Volume (cc/mol): 70.0

Covalent Radius (pm): 235

Ionic Radius: 167 (+1e)

Specific Heat (@20°C J/g mol): 0.241

Fusion Heat (kJ/mol): 2.09

Evaporation Heat (kJ/mol): 68.3

Pauling Negativity Number: 0.79

First Ionizing Energy (kJ/mol): 375.5

Oxidation States: 1

Electronic Configuration: [Xe] 6s1

Lattice Structure: Body-Centered Cubic

Lattice Constant (Å): 6.050

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952)


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