Francium · Fr Francium
is an extremely short-lived alkali metal, mainly used for research on atomic and nuclear structures.
- atomic number / Atomic number
- 87
- atomic weight / Atomic mass
- 223.01973 u
- Family/Group
- 1
- Period · Block / Period · Block
- 7 · s
- Category / Category
- Alkali metal · Alkali metal
- State / State
- solid state
- Electron configuration
- [Rn]7s1
- Oxidation states / Oxidation states
- +1
- Electronegativity / Electronegativity
- 0.7（Pauling）
- Density / Density
- not included
- Melting point / Melting point
- 300 K
- Boiling point / Boiling point
- not included
- Atomic radius / Atomic radius
- 348 pm（van der Waals）
- First ionization energy
- 3.9 eV
- Discovery year / Discovery
- 1939
attribute description and data source
properties taken from PubChem periodic table snapshot (2026-10-04). Atomic weights may be reference values or representative isotope masses and cannot be considered exact constants for all samples; density, phase transition points, and phase states depend on temperature, pressure, and allotropes. The solidification of helium requires pressure. Some properties of radioactive and superheavy elements are predicted values, and missing items are marked as not included. Please check the original source and experimental conditions for precise calculations.