Details : Item 215

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Alkali metals
Alkaline earth metal
Transition metals I
Transition metals II
Transition metals III
Transition metals IV
Post-transition metal
Metalloid
Diatomic non-metal
Noble gas
Other

Famille : Alkali metals/5
Caesium
Symbol: Cs, phase:solid, silvery gold
Widely used in highly accurate atomic clocks.
As caesium formate used for drilling fluids. Highly reactive,
it reacts explosively with water even at low temperatures.
Properties
Atomic number55
Atomic weight132.905
Melting point (K)301.7
Boiling point (K)944
Speed of sound (m/s)1.8
Discovery1860 (G. Kirchhoff)