Periodic TableFrancium (Fr)
Francium is an alkali metal with atomic number 87, in period 7 and group 1 of the periodic table. Its atomic mass is 223 u and its electron configuration is [Rn] 7s¹. Solid at 25 °C.
Key facts
| Atomic number | 87 |
|---|---|
| Atomic mass | 223 u |
| Category | Alkali Metal |
| Period | 7 |
| Group | 1 |
| Block | s |
| Electron configuration | [Rn] 7s¹ |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 1 |
| Electronegativity (Pauling) | 0.7 |
| Oxidation states | +1common in bold |
| State at 25 °C | Solid |
| Melting point | 300 K26.85 °C |
| Boiling point | 950 K676.85 °C |
| Density | 2.48 g/cm³ |
Atomic properties
| First ionization energy | 4.073 eV |
|---|---|
| Electron affinity | 45.3 kJ/mol |
| Atomic radius | 290 pm |
| Covalent radius | 260 pm |
| Van der Waals radius | 348 pm |
| Common ions | Fr_{+} |
| Protons, neutrons, electrons | 87, 136, 87 |
Physical and thermal properties
| Molar volume | 77 cm³/mol |
|---|---|
| Heat of fusion | 2 kJ/mol |
| Heat of vaporization | 64 kJ/mol |
| Specific heat | --- |
| Thermal conductivity | --- |
| Thermal expansion | --- |
| Mohs hardness | --- |
| Young’s modulus | --- |
| Crystal structure | --- |
| Magnetic type | --- |
Identification and history
| CAS number | 7440-73-5 |
|---|---|
| Latin name | Francium |
| Discovered by | Marguerite Perey · 1939 |
| Named by | --- |
Natural isotopes
Francium has no stable isotopes: every isotope is radioactive.
Data checked against PubChem (NIH), IUPAC, the NIST Atomic Spectra Database and the IAEA (NUBASE and AME), the same data you see in the app.
A dash (---) means there is no reliable published measurement. The app never makes one up.
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