Californium Element Facts

General
States
Energies
Oxidation & Electrons
Appearance & Characteristics
Reactions & Compounds
Radius
Conductivity
Abundance & Isotopes

98 Cf 251 Californium

Californium is Radioactive.

Name: Californium
Type: Actinide
Density @ 293 K: 13.67 g/cm³

Discovery of Californium
Californium was the sixth synthetic transuranium element of the actinide series to be discovered.

It was first produced by Stanley Thompson, Kenneth Street, Albert Ghiorso and Glenn Seaborg in 1950 in California, USA.

The researchers bombarded curium-242 with alpha particles in the 60-inch cyclotron in Berkeley, California. Each nuclear reaction created californium-245 (half-life 44 minutes) and a neutron. Only about 700,000 atoms of californium-245 were produced in the experiment. This number of atoms is enough to make a cube with sides about 27 nanometers long. Chemical analysis proved that the new element had been made. ⁽¹⁾

Californium was isolated in macro quantities for the first time by Burris Cunningham and Stanley Thompson in 1958 by prolonged (five years) neutron irradiation of plutonium-239. Approximately 1.2 micrograms of californium and 0.6 micrograms of berkelium were synthesized. ^(1a)

The element was named after the U.S. State of California and the University of California.

Symbol: Cf
Atomic weight: 251
Atomic volume: 18.4 cm³/mol

State (s, l, g): solid
Melting point: 1173 K   (900 ^oC)

Boiling point: 1745 K   (1472 ^oC) (estimated)

Specific heat capacity: J g^-1 K^-1
Heat of fusion: kJ mol^-1
1^st ionization energy: 608 kJ mol^-1
3^rd ionization energy: kJ mol^-1

Heat of atomization: kJ mol^-1
Heat of vaporization: kJ mol^-1
2^nd ionization energy: kJ mol^-1
Electron affinity: kJ mol^-1

Shells: 2,8,18,32,28,8,2
Minimum oxidation number: 0
Min. common oxidation no.: 0
Electronegativity (Pauling Scale): 1.3

Electron configuration: [Rn] 5f¹⁰ 7s²
Maximum oxidation number: 4
Max. common oxidation no.: 3
Polarizability volume: 20.5 ų

Structure: double hexagonal close-packed
Hardness: mohs

Color: silvery-white


Harmful effects:
Californium is harmful due to its radioactivity.

Characteristics:
Californium is a synthetic radioactive silvery-white metal of moderate chemical reactivity. It is a relatively soft, malleable metal and is easily cut with a razor-blade. It slowly tarnishes in air to the oxide at room temperature. ⁽²⁾ Californium-252 is a very strong neutron emitter.

Uses:
Californium-252 (half-life of 2.645 years) is produced in nuclear reactors and has found a variety of uses.

It is used as a neutron emitter, providing neutrons for the start-up of nuclear reactors.

It has also been used as a target material for producing transcalifornium elements. Ununoctium, the heaviest of the elements, was produced when a californium target was bombarded with calcium ions. ^(2a)

Californium-252 is used in to treat cervical cancer. It is also used to analyze the sulfur content of petroleum and in neutron moisture gauges to measure the moisture content of soil. ⁽³⁾

Reaction with air:
Reaction with 15 M HNO₃:
Oxide(s): CfO, Cf₂O₃, CfO₂ , Cf₇O₁₂
Hydride(s):

Reaction with 6 M HCl:
Reaction with 6 M NaOH:
Chloride(s): CfCl₃

Atomic radius: 186 pm
Ionic radius (2+ ion): pm
Ionic radius (2- ion): pm

Ionic radius (1+ ion): pm
Ionic radius (3+ ion): 109 pm
Ionic radius (1- ion): pm

Thermal conductivity: 10 W m^-1 K^-1

Electrical conductivity: x 10⁶ S cm^-1