87FrFrancium223[Rn] 7s¹
alkali metal
Francium
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.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
Electrons by shell
Electron configuration
7s1
86 is the [Rn] core total across six shells.
At a glance
- Atomic number
- 87
- Atomic mass
- 223 u
- Phase
- Solid
- Density
- 1.87 g/cm³
- Melting point
- 300 K
- Boiling point
- 950 K
- First ionization energy
- 380 kJ/mol
- Electronegativity
- 0.79
- Electron affinity
- 46.89 kJ/mol
- Molar heat capacity
- Unavailable
- Period
- 7
- Appearance
- Unavailable
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
Keep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.