Francium (Fr)
Alkali metal · s-block · period 7 · group 1
Never seen in bulk; a visible amount would instantly melt and boil from its own radioactivity.
Francium (symbol Fr) is chemical element number 87, a alkali metal in group 1, period 7 of the periodic table. Its standard atomic weight is (223) and its electron configuration is [Rn] 7s1. At room temperature it is a solid, and it is radioactive. The last element discovered in nature, by a woman scientist who named it after France.
Properties
| Atomic number | 87 |
|---|---|
| Atomic mass | (223) |
| Category | Alkali metal |
| Block | s-block |
| Group · Period | 1 · 7 |
| Electron configuration | [Rn] 7s1 |
| Electrons per shell | 2, 8, 18, 32, 18, 8, 1 |
| State at 25 °C | solid |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | 0.7 |
| Radioactive | Yes — no stable isotope |
| Origin | decay |
| Discovered | 1939 · Marguerite Perey |
Key facts about Francium
- The last element discovered in nature, by a woman scientist who named it after France.
- The most unstable of the first 101 elements — its longest-lived form lasts only 22 minutes.
- At most about 30 grams exist in the entire Earth's crust at any time.
- The second most electropositive element, after caesium.
What Francium is used for
None practical — used only in tiny amounts for atomic-structure research.
Where it sits in the periodic table
Francium is in group 1, period 7, of the s-block. Its electron configuration [Rn] 7s1 means its outermost shell holds 1 electron, which is what places it here and explains much of its chemistry. See Francium on the interactive table →
Francium — frequently asked questions
What is Francium used for?
None practical — used only in tiny amounts for atomic-structure research.
Is Francium radioactive?
Yes. Francium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Francium?
Francium has the electron configuration [Rn] 7s1, which is 2, 8, 18, 32, 18, 8, 1 electrons per shell.
What group and period is Francium in?
Francium is in group 1, period 7, in the s-block. Its outer shell holds 1 electron.
Who discovered Francium?
Francium was discovered in 1939 by Marguerite Perey.