87Fr223.000
Alkali Metals-blockRadioactive
Francium
Element 87 on the periodic table, symbol Fr, group 1, period 7.
Francium 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.
Properties
- Atomic Number
- 87
- Atomic Mass
- 223.0000 u
- Group
- 1
- Period
- 7
- Block
- s-block
- Category
- Alkali Metal
- State at 25 °C
- Solid
- Melting Point
- 300 K · 26.9 °C
- Boiling Point
- 950 K · 676.9 °C
- Density
- 1.87 g/cm³
- Atomic Radius
- 260 pm
- Electronegativity
- 0.79
- Oxidation States
- +1
- Abundance in Crust
- 1.00e-18 mg/kg
- Discovered
- 1939
- Discovered By
- Marguerite Perey
Electron Configuration
[Rn] 7s1
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1
Ionisation Energies (kJ/mol)
- 1. 380
Elements near Francium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.