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87Fr223.000
Francium
Alkali MetalFrancium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon.
Phase: Solid
2, 8, 18, 32, 18, 8, 1
Physical Properties
Atomic Mass223 u
Density1.87 g/cm³
Melting Point300 K
Boiling Point950 K
Period7
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1
Semantic Config[Rn] 7s1
Shells2, 8, 18, 32, 18, 8, 1
Electron Affinity46.89 kJ/mol
Electronegativity0.79
Ionization Energies
IE1: 380 kJ/mol
Discovery
Discovered byMarguerite Perey