Atomic Number 55     Atomic Mass 132.905429     Density 1.8785 g/mL

State solid   Color silvery white    Electronegativity 0.79

Melting Point 28.40°C      Boiling Point 669.3°C

Natural Isotope Cs-133 100%

Abbreviated Electron Configuration [Xe] 6s¹

Discovered by Robert Bunsen and Gustav Kirchhoff in 1860.