Element 98
Californium (Cf)
Californium (Cf) is element 98 of the periodic table, a actinide in period 7 (f-block) with an atomic mass of 251 and is a solid at standard conditions.
At a glance
- Atomic number
- 98
- Symbol
- Cf
- Atomic mass
- 251 u
- Category
- Actinides
- Period
- 7
- Block
- f-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f10 7s2
- Shorthand configuration
- [Rn] 5f10 7s2
- Electrons per shell
- 2, 8, 18, 32, 28, 8, 2
- Oxidation states
- +2, +3, +4
Physical properties
- Melting point
- 1173 K
- Boiling point
- 1743 K
- Density
- 15.1 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.3
- Atomic radius
- 186 pm
- First ionization energy
- 608 kJ/mol
- Electron affinity
- -97 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Cf-251 | 251.07959 | — | Half-life 900 years |
Common uses
- Neutron sources
- Metal detection
- Cancer treatment
- Oil well logging
Discovery
- Year
- 1950
- Discovered by
- Stanley G. Thompson, Kenneth Street Jr., Albert Ghiorso, Glenn T. Seaborg
- Country
- USA