98Cf[251]
Californium (Cf)
Element 98 · Actinide
Californium (Cf) is a chemical element with atomic number 98. It is classified as an actinide in period 7 of the periodic table (the f-block). Its most stable known isotope has mass number 251 and its ground-state electron configuration is [Rn] 5f¹⁰ 7s².
Californium facts
| Atomic number (Z) | 98 |
|---|---|
| Symbol | Cf |
| Mass number of most stable isotope | [251] |
| Category | Actinide |
| Group | — (f-block) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f¹⁰ 7s² |
| Electronegativity (Pauling) | 1.3 |
| State at 20 °C | Solid |
| Protons / electrons | 98 / 98 |
| Neutrons (most common isotope, approx.) | 153 |
| Molar mass | 251 g/mol |