87223FrFrancium
Francium (Fr) — element 87alkali metal · group 1, period 7
Francium is a chemical element with the symbol Fr and atomic number 87. It is an alkali metal in group 1, period 7 of the periodic table (the s-block), with a standard atomic mass of 223 u. At room temperature (25 °C) francium is a solid.
💡 Known for: Extremely rare and radioactive; the last element to be discovered in nature (1939).
# Francium properties
| Symbol | Fr |
|---|---|
| Atomic number | 87 |
| Atomic mass | 223 u |
| Category | alkali metal |
| Group | 1 |
| Period | 7 |
| Block | s-block |
| Electron configuration | [Rn] 7s¹ |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s¹ |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 1 |
| Protons / electrons | 87 / 87 |
| State at 25 °C | solid |
| Melting point | 300 K (26.9 °C, 80.3 °F) |
| Boiling point | 950 K (676.9 °C, 1250.3 °F) |
| Density | 1.87 g/cm³ |
| Electronegativity (Pauling) | 0.7 |
| First ionization energy | 4.073 eV |
| Atomic radius | 348 pm |
| Discovered | 1939 |
# Electron configuration of francium
The electron configuration of francium is [Rn] 7s¹, written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s¹. Its 87 electrons fill 7 shells as 2, 8, 18, 32, 18, 8, 1, so the outermost shell holds 1 electron. As a group 1 element, francium has 1 valence electron.
# Related elements
RnRadonprevious elementRaRadiumnext elementHHydrogengroup 1LiLithiumgroup 1NaSodiumgroup 1KPotassiumgroup 1RbRubidiumgroup 1CsCaesiumgroup 1
# Francium FAQ
What is the atomic number of francium?
The atomic number of francium is 87: every francium atom has 87 protons in its nucleus. Its symbol is Fr.
What is the atomic mass of francium?
The standard atomic mass of francium is 223 u.
What is the electron configuration of francium?
Francium's electron configuration is [Rn] 7s¹ (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s¹), with 2, 8, 18, 32, 18, 8, 1 electrons per shell.
Is francium a metal?
Yes. Francium is an alkali metal, one of the metals.
What is the melting point of francium?
Francium melts at 300 K (26.9 °C, 80.3 °F) and boils at 950 K (676.9 °C, 1250.3 °F).
What is francium used for / known for?
Extremely rare and radioactive; the last element to be discovered in nature (1939).