Quick answerCalifornium (Cf) is an actinide with atomic number 98 and a mass number of 251 (the most stable isotope), in period 7. It was discovered by Thompson, Street, Ghiorso, and Seaborg in 1950. It is used for reactor start-up neutron sources and cargo scanning. Its electron configuration is [Rn] 5f10 7s2.
Californium is a powerful neutron source that starts up nuclear reactors and scans cargo for hidden explosives.
Key facts
| Symbol | Cf |
|---|---|
| Atomic number | 98 |
| Atomic mass | [251] — mass number of the most stable isotope |
| Category | actinide |
| Group | — (f-block element, no group number) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f10 7s2 |
| Discovered | Thompson, Street, Ghiorso, and Seaborg, 1950 |
| Uses | reactor start-up neutron sources, cargo scanning, oil well logging, research |
Quick quiz
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Keep exploring
- Periodic table — all 118 elements
- Neptunium (Np) — another actinide, atomic number 93
- Plutonium (Pu) — another actinide, atomic number 94
- Americium (Am) — another actinide, atomic number 95
- Curium (Cm) — another actinide, atomic number 96
- Berkelium (Bk) — another actinide, atomic number 97
- Einsteinium (Es) — another actinide, atomic number 99
- Fermium (Fm) — another actinide, atomic number 100
- Mendelevium (Md) — another actinide, atomic number 101
- Nobelium (No) — another actinide, atomic number 102
- Lawrencium (Lr) — another actinide, atomic number 103
- All actinide elements — on the periodic table
Sources & last updated
- CIAAW — Standard Atomic Weights
- PubChem Periodic Table
- Wikipedia — Timeline of chemical element discoveries
Last updated: . Figures are shown with their year; where sources disagree, the value is left out rather than estimated.