87Fr[223]
Francium (Fr)
Element 87 Ā· Alkali metal
Francium (Fr) is a chemical element with atomic number 87. It is classified as an alkali metal in period 7, group 1 of the periodic table (the s-block). Its most stable known isotope has mass number 223 and its ground-state electron configuration is [Rn] 7sĀ¹.
Francium facts
| Atomic number (Z) | 87 |
|---|---|
| Symbol | Fr |
| Mass number of most stable isotope | [223] |
| Category | Alkali metal |
| Group | 1 |
| Period | 7 |
| Block | s-block |
| Electron configuration | [Rn] 7sĀ¹ |
| Electronegativity (Pauling) | 0.7 |
| State at 20 Ā°C | Solid |
| Protons / electrons | 87 / 87 |
| Neutrons (most common isotope, approx.) | 136 |
| Molar mass | 223 g/mol |