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/6
Francium
Symbol: Fr, phase: solid presumably
Bulk francium has never been viewed. As little
as 2030 g exists at any given time throughout the Earth s
crust. The largest amount produced was a cluster of 300,000 atoms.
Properties
Atomic number87
Atomic weight223
Melting point (K)300
Boiling point (K)950
Speed of sound (m/s)N/A
Discovery1939 (M. Perey)