Francium

Chaitra 26/06/2026 19:58:09 Updated 26/06/2026 19:58:09

Property	Value
Atomic Number	87
Element	Francium
Symbol	Fr
Atomic Mass	[223] (most stable isotope)
Number of Neutrons	136 (Francium-223)
Number of Protons	87
Number of Electrons	87
Period	7
Group	1
Phase	Solid (predicted)
Radioactive	Yes
Natural	Yes (trace amounts from decay of uranium)
Metal	Yes
Nonmetal	No
Metalloid	No
Type	Alkali Metal
Atomic Radius	~348 pm (estimated)
Electronegativity	0.70 (estimated)
First Ionization Energy	4.072 eV (estimated)
Density	~1.87 g/cm³ (estimated)
Melting Point	~27 °C (estimated)
Boiling Point	~677 °C (estimated)
Number of Isotopes	No stable isotopes (Fr-223 most notable)
Discoverer	Marguerite Perey
Year	1939
Specific Heat	— (not well established)
Number of Shells	7
Number of Valence Electrons	1