Californium
A powerful neutron source used to start reactors and scan ores.
Inside the Californium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Californium atom step by step.
Electron configuration
[Rn] 5f10 7s2
A neutral Californium atom has 98 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 1173 K (900 °C)
- Boiling point
- 1743 K (1470 °C)
- Density
- 15.1 g/cm³
- Electronegativity
- 1.3 Pauling
- Atomic radius
- —
- 1st ionization energy
- 608 kJ/mol
- Category
- Actinides
Discovery & naming
- Discovered
- 1950
- Discovered by
- Glenn Seaborg and colleagues
- Origin of name
- The state of California.
Notable uses
Portable neutron sources and cancer treatment.
Where Californium comes from
Human synthesis
Synthetic and intensely radioactive; reactor-made, and used as a portable neutron source.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 98
- Atomic mass
- [251]
- Category
- Actinides
- Group · Period
- — · 7
- Block
- f-block
- Shells
- 2 · 8 · 18 · 32 · 28 · 8 · 2