Francium (Fr)
Alkali metal · Radioactive
Francium is the most unstable of the first 101 elements — its longest-lived isotope lasts 22 minutes. It was the last element discovered in nature, found by Marguerite Perey, a technician trained by Marie Curie.
Position on the periodic table
Atomic properties
| Atomic number | 87 |
|---|---|
| Atomic mass | 223 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1 |
| Noble gas shorthand | [Rn] 7s1 |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 1 |
| Valence electrons (outer shell) | 1 |
| Common oxidation states | +1 |
| Electronegativity (Pauling) | 0.79 |
| Covalent radius (approx.) | 260 pm |
| First ionization energy | 380 kJ/mol |
| Electron affinity | 46.9 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 1.87 g/cm³ |
| Melting point | 26.85 °C (300 K) |
| Boiling point | 676.85 °C (950 K) |
| Appearance | Not available |
| Radioactive | Yes |
| Origin | Occurs naturally |
Electron configuration of francium
Francium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s1, usually shortened to [Rn] 7s1. Its electrons occupy 7 shells (2, 8, 18, 32, 18, 8, 1), placing it in period 7 of the s-block. The 1 outer-shell electron drives its bonding behaviour. Explore it interactively in the electron configuration calculator.
Uses of francium
- Fundamental atomic physics research only
Biological role: None.
Occurrence: Fleeting traces in uranium minerals from actinium decay.
History and discovery
Discovered: 1939 — Marguerite Perey. Name origin: Named after France, homeland of its discoverer Marguerite Perey.
Marguerite Perey discovered francium in 1939 while purifying actinium at the Curie Institute in Paris.
Safety notes
Intensely radioactive; only ever handled as a few thousand atoms in traps.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Francium
1. What is the chemical symbol of Francium?
2. What is the atomic number of Francium?
3. Which category does Francium belong to?
4. What is the state of Francium at room temperature?
5. Which period of the periodic table is Francium in?
Francium FAQs
What is the atomic number of francium?
Francium's atomic number is 87 — every francium atom has 87 protons in its nucleus.
What is the symbol for francium?
Fr. Named after France, homeland of its discoverer Marguerite Perey.
Is francium a metal, nonmetal, or metalloid?
Francium is classified as a alkali metal.
What state is francium at room temperature?
At about 25 °C, francium is a solid. It melts at 26.85 °C.
How many valence electrons does francium have?
Francium has 1 electron in its outer shell (shell pattern: 2, 8, 18, 32, 18, 8, 1).
What is francium used for?
Key uses include: fundamental atomic physics research only.
Related elements
Keep working with this element
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