Francium (Fr)
Francium is element 87, a alkali metal in period 7, group 1 of the periodic table. At room temperature it is a solid.
Electron configuration [Rn] 7s1
Electrons per shell 2, 8, 18, 32, 18, 8, 1
Francium data
| Atomic number | 87 |
|---|---|
| Symbol | Fr |
| Atomic mass | [223] (mass number of the longest-lived isotope) |
| Category | Alkali metal |
| Group | 1 |
| Period | 7 |
| Block | s |
| State at 25 °C | solid |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | 0.7 |
| Atomic radius | — |
| 1st ionization energy | 380 kJ/mol |
| Electron affinity | — |
| Oxidation states | +1 |
| Common ion charge | + |
| Discovered | 1939 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through francium’s configuration and its ions →
Where francium sits
Francium belongs to the alkali metals. Its Pauling electronegativity of 0.7 is among the lowest on the table, so it gives up electrons readily; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Francium FAQ
What is the electron configuration of francium?
Francium (Z = 87) has the configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 7s1. In noble-gas shorthand that is [Rn] 7s1.
How many valence electrons does francium have?
1 (outer shell (n = 7)).
What is the atomic mass of francium?
Francium has no stable isotopes. Its most stable known isotope has mass number 223, so tables list [223].
Is francium a metal?
Yes. Francium is a alkali metal.
What is the charge of a francium ion?
Francium most commonly forms Fr+.