Cesium (Cs)

From Wikipedia, the free encyclopediaCaesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold alkali metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium is an alkali metal and has physical and chemical properties similar to those of rubidium and potassium.

Cesium in the periodic table

SymbolCs
Atomic number55
Group1
Period6
Blocks
Element categoryAlkali Metal

Physical properties

Phase at STPSolid
Density1.93 g/cm3
Atomic weight132.905 u
Melting point301.7 K
28.55 °C
83.39 °F
Boiling point944 K
670.85 °C
1239.53 °F

Atomära egenskaper

Electronegativity (Pauling Scale)0.79
Electron affinity45.505 kJ/mol
Ionization energies
1375.7 kJ/mol
2 2234.3 kJ/mol
3 3400 kJ/mol

Electron configuration

Electron configuration1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s1
Electrons per shell2, 8, 18, 18, 8, 1

History

Discovered1860
Discovered byRobert Bunsen
Gustav Kirchhoff