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Californium

Element 98 · Actinide

Specimen

Atomic number
98
Atomic mass
251.08
State at room temperature
Solid
Melting point
899.9 °C
Boiling point
Unknown
Density
Unknown
Discovered
1950

Physical data from PubChem.1

Can I eat it?

In food and water
Radioactive. All californium is radioactive. Reactors make it in milligram amounts only. Its radiation is the main danger. 2

See every element.

The atom

Cf
ShellElectrons
1 (K) 2
2 (L) 8
3 (M) 18
4 (N) 32
5 (O) 28
6 (P) 8
7 (Q) outermost 2
Total98

Configuration [Rn] 5f¹⁰ 7s²

5f ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↑ ↑ ↑
7s ↑ ↓
A shell diagram: each ring is an electron shell and each dot is one electron. The nucleus holds 98 protons. The outermost shell is shown in red. Electrons do not travel on rings: they fill orbitals, regions where an electron is likely to be found. The boxes are those orbitals for the electrons outside the Rn core, with one arrow per electron.

Related elements

Actinides
Ac Actinium Th Thorium Pa Protactinium U Uranium Np Neptunium Pu Plutonium Am Americium Cm Curium Bk Berkelium Es Einsteinium Fm Fermium Md Mendelevium No Nobelium Lr Lawrencium

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Sources

  1. 1

    National Center for Biotechnology Information (PubChem), 2026. Periodic Table of Elements .

    Atomic mass, electron configuration, melting and boiling points, density and discovery year for all 118 elements.

  2. 2

    Royal Society of Chemistry, Periodic Table, 2026. Californium - Element information, properties and uses .

    Reference page; its Biological role and Natural abundance sections are quoted.

    • Californium has no known biological role. It is toxic due to its radioactivity. ... It is prepared, in milligram amounts only, by the neutron bombardment of plutonium-239.