About

Californium is a radioactive element named after the state and university of California. It is a very strong neutron emitter, with one microgram of californium-252 emitting over 100 million neutrons per minute. This unique property makes it useful for starting up nuclear reactors, in material scanners for luggage inspection, and as a radiation source for certain types of cancer treatment.

Atomic Properties

Atomic Number98

Atomic Weight251 u

Neutrons (common)153

Electron Configuration[Rn] 5f¹⁰ 7s²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 5f¹⁰ 7s²

Electrons per Shell2, 8, 18, 32, 28, 8, 2

Electronegativity1.3

Oxidation States+2, +3, +4

Ionic Radius95 pm

Periodic Table Position

Group3

Period7

BlockF

Chemical SeriesActinoids

Physical Properties

State at STPsolid

Appearancesilvery-white metallic

Crystal Structurehcp

Magnetic Orderingparamagnetic

Thermal Properties

Melting Point1,173 K

Boiling Point1,743 K

Thermal Conductivity10 W/(m·K)

Heat of Vaporization162 kJ/mol

Discovery

Discovered byGlenn T. Seaborg, Stanley G. Thompson, Kenneth Street, Jr., Albert Ghiorso

Discovery Year1,950

Occurrencesynthetic

CAS Number7440-71-3

Electron Configuration

Energy

↿⇂

1s

↿⇂

2s

↿⇂

2p

↿⇂

3s

↿⇂

3p

↿⇂

4s

↿⇂

3d

↿⇂

4p

↿⇂

5s

↿⇂

4d

↿⇂

5p

↿⇂

6s

↿⇂

4f

↿⇂

5d

↿⇂

6p

↿⇂

7s

↿⇂

↿

5f

6d

7p

Isotopes of Californium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
²⁴⁹Cf	249.074850	—	351 y	Alpha Decay, Spontaneous Fission
²⁵⁰Cf	250.076400	—	13.08 y	Alpha Decay, Spontaneous Fission
²⁵¹Cf	251.079580	—	898 y	Alpha Decay