Californium

Californium (Cf)

Radioactive metallic transuranic element. Belongs to actinoid series. Cf-251 has a half life of about 700 years. Nine isotopes are known. Cf-252 is an intense Neutron source, which makes it an intense Neutron source and gives it a use in Neutron activation analysis and a possible use as a radiation source in medicine. First produced by Glenn T. Seaborg and associates in 1950.
Atomic Number98
Atomic Weight251
Mass Number237
Group
Period7
Blockf
Protons98 p+
Neutrons139 n0
Electrons98 e-
Californium.jpg Animated Bohr Model of Cf (Californium) Enhanced Bohr Model of Cf (Californium) Bohr Model: Cf (Californium) Orbital Diagram of Cf (Californium)

Properties

Atomic Radius
Molar Volume
Covalent Radius
168 pm
Metallic Radius
Ionic Radius
95 pm
Crystal Radius
109 pm
Van der Waals Radius
245 pm
Density
15.1 g/cm³
Energy
Proton Affinity
Electron Affinity
Ionization Energy
Heat of Vaporization
Heat of Fusion
Heat of Formation
196 kJ/mol
Electrons
Electron Shells2, 8, 18, 32, 28, 8, 2
Valence Electrons4
Electron Configuration[Rn] 5f10 7s2
Oxidation States2, 3, 4, 5
Electronegativity
Electrophilicity
Phases
PhaseSolid
Gas Phase
Boiling Point
Melting Point
1,173.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color
Colorless
Appearancesilvery
Refractive Index
Thermodynamic Properties
Thermal Conductivity
Thermal Expansion
Molar Heat Capacity
Specific Heat Capacity
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type
Electrical Conductivity
Electrical Resistivity
Superconducting Point
Magnetism
Type
Magnetic Susceptibility (Mass)
Magnetic Susceptibility (Molar)
Magnetic Susceptibility (Volume)
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal StructureSimple Hexagonal ()
Lattice Constant
Lattice Anglesπ/2, π/2, 2 π/3
Mechanical Properties
Hardness
Bulk Modulus
Shear Modulus
Young Modulus
Poisson Ratio
Speed of Sound
Classification
CategoryActinides, Actinides
CAS Group
IUPAC Group
Glawe Number42
Mendeleev Number32
Pettifor Number39
Geochemical Class
Goldschmidt Classsynthetic
Other
Gas Basicity
Dipole Polarizability
122 ± 20 a₀
C6 Dispersion Coefficient
Allotropes
Neutron Cross Section
2,900
Neutron Mass Absorption
Quantum Numbers5I8
Space Group194 (P63/mmc)

Isotopes of Californium

Stable Isotopes0
Unstable Isotopes20
Radioactive Isotopes20

237Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
237.062199272 ± 0.000104506 Da
Mass Number237
G-Factor
Half Life
0.8 ± 0.2 s
Spin5/2
Quadrupole Moment
Discovery Year1995
Parity+

237Cf Decay Modes
Decay ModeIntensity
α (α emission)70%
SF (spontaneous fission)30%
β+ (β+ decay; β+ = ϵ + e+)%

238Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
238.06149 ± 0.00032 Da
Mass Number238
G-Factor
0
Half Life
21.1 ± 1.3 ms
Spin0
Quadrupole Moment
0
Discovery Year1995
Parity+

238Cf Decay Modes
Decay ModeIntensity
SF (spontaneous fission)97.5%
α (α emission)2.5%

239Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
239.062482 ± 0.000129 Da
Mass Number239
G-Factor
Half Life
28 ± 2 s
Spin5/2
Quadrupole Moment
Discovery Year1981
Parity+

239Cf Decay Modes
Decay ModeIntensity
α (α emission)65%
β+ (β+ decay; β+ = ϵ + e+)%

240Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
240.062253447 ± 0.00001936 Da
Mass Number240
G-Factor
0
Half Life
40.3 ± 0.9 s
Spin0
Quadrupole Moment
0
Discovery Year1970
Parity+

240Cf Decay Modes
Decay ModeIntensity
α (α emission)98.5%
SF (spontaneous fission)1.5%
β+ (β+ decay; β+ = ϵ + e+)%

241Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
241.06369 ± 0.00018 Da
Mass Number241
G-Factor
Half Life
2.35 ± 0.18 m
Spin7/2
Quadrupole Moment
Discovery Year1970
Parity-

241Cf Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)%
α (α emission)15%

242Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
242.063754544 ± 0.00001384 Da
Mass Number242
G-Factor
0
Half Life
3.49 ± 0.15 m
Spin0
Quadrupole Moment
0
Discovery Year1967
Parity+

242Cf Decay Modes
Decay ModeIntensity
α (α emission)61%
β+ (β+ decay; β+ = ϵ + e+)39%
SF (spontaneous fission)0.014%

243Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
243.065475 ± 0.000194 Da
Mass Number243
G-Factor
Half Life
10.8 ± 0.3 m
Spin1/2
Quadrupole Moment
0
Discovery Year1967
Parity+

243Cf Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)86%
α (α emission)14%

244Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
244.065999447 ± 0.000002809 Da
Mass Number244
G-Factor
0
Half Life
19.5 ± 0.5 m
Spin0
Quadrupole Moment
0
Discovery Year1956
Parity+

244Cf Decay Modes
Decay ModeIntensity
α (α emission)75%
ϵ (electron capture)25%

245Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
245.068046755 ± 0.000002606 Da
Mass Number245
G-Factor
Half Life
45 ± 1.5 m
Spin1/2
Quadrupole Moment
0
Discovery Year1956
Parity+

245Cf Decay Modes
Decay ModeIntensity
β+ (β+ decay; β+ = ϵ + e+)64.7%
α (α emission)35.3%

246Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
246.068803685 ± 0.000001625 Da
Mass Number246
G-Factor
0
Half Life
35.7 ± 0.5 h
Spin0
Quadrupole Moment
0
Discovery Year1951
Parity+

246Cf Decay Modes
Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)2.4%
ϵ (electron capture)%

247Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
247.070971348 ± 0.00001538 Da
Mass Number247
G-Factor
Half Life
3.11 ± 0.03 h
Spin7/2
Quadrupole Moment
Discovery Year1954
Parity+

247Cf Decay Modes
Decay ModeIntensity
ϵ (electron capture)99.965%
α (α emission)0.035%

248Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
248.072182905 ± 0.000005497 Da
Mass Number248
G-Factor
0
Half Life
333.5 ± 2.8 d
Spin0
Quadrupole Moment
0
Discovery Year1954
Parity+

248Cf Decay Modes
Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)0.0029%

249Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
249.074850428 ± 0.000001269 Da
Mass Number249
G-Factor
Half Life
351 ± 2 y
Spin9/2
Quadrupole Moment
Discovery Year1954
Parity-

249Cf Decay Modes
Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)5%

250Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
250.076404494 ± 0.00000165 Da
Mass Number250
G-Factor
0
Half Life
13.08 ± 0.09 y
Spin0
Quadrupole Moment
0
Discovery Year1954
Parity+

250Cf Decay Modes
Decay ModeIntensity
α (α emission)99.923%
SF (spontaneous fission)0.077%

251Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
251.079587171 ± 0.000004187 Da
Mass Number251
G-Factor
Half Life
898 ± 44 y
Spin1/2
Quadrupole Moment
0
Discovery Year1954
Parity+

251Cf Decay Modes
Decay ModeIntensity
α (α emission)100%
SF (spontaneous fission)%

252Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
252.081626507 ± 0.000002531 Da
Mass Number252
G-Factor
0
Half Life
2.645 ± 0.008 y
Spin0
Quadrupole Moment
0
Discovery Year1954
Parity+

252Cf Decay Modes
Decay ModeIntensity
α (α emission)96.8972%
SF (spontaneous fission)3.1028%

253Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
253.085133723 ± 0.00000457 Da
Mass Number253
G-Factor
Half Life
17.81 ± 0.08 d
Spin7/2
Quadrupole Moment
Discovery Year1954
Parity+

253Cf Decay Modes
Decay ModeIntensity
β (β decay)99.69%
α (α emission)0.31%

254Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
254.087323575 ± 0.000012304 Da
Mass Number254
G-Factor
0
Half Life
60.5 ± 0.2 d
Spin0
Quadrupole Moment
0
Discovery Year1955
Parity+

254Cf Decay Modes
Decay ModeIntensity
SF (spontaneous fission)99.69%
α (α emission)0.31%
(double β decay)%

255Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
255.091046 ± 0.000215 Da
Mass Number255
G-Factor
Half Life
85 ± 18 m
Spin7/2
Quadrupole Moment
Discovery Year1981
Parity+

255Cf Decay Modes
Decay ModeIntensity
β (β decay)100%
SF (spontaneous fission)%
α (α emission)%

256Cf

AbundanceRadioactive ☢️
Relative Atomic Mass
256.093442 ± 0.000338 Da
Mass Number256
G-Factor
0
Half Life
12.3 ± 1.2 m
Spin0
Quadrupole Moment
0
Discovery Year1980
Parity+

256Cf Decay Modes
Decay ModeIntensity
SF (spontaneous fission)100%
α (α emission)%
(double β decay)%

History

Californium was discovered by Stanley G. Thompson, Kenneth Street, Jr., Albert Ghiorso and Glenn T. Seaborg in 1950 at the University of California, Berkeley. It was produced by the bombardment of curium with alpha particles. Californium was isolated in macro quantities for the first time by Burris Cunningham and Stanley Thompson in 1958. Named after California and the University of California

DiscoverersG.T.Seaborg, S.G.Tompson, A.Ghiorso, K.Street Jr.
Discovery LocationUnited States
Discovery Year1950
Etymology (Name Origin)Named after the state and University of California.
Pronunciationkal-eh-FOR-ni-em (English)
Californium is harmful due to its radioactivity
Californium is produced in nuclear reactors and particle accelerators

Uses

Californium is used as a portable neutron source for discovery of metals such as gold or silver by on-the-spot activation analysis. Neutrons from californium are employed as a treatment of certain cervical and brain cancers where other radiation therapy is ineffective. Neutron moisture gauges use californium-252 to find water and petroleum layers in oil wells. It has no significant commercial applications.

Sources

Made by bombarding curium with helium ions.

Abundance
Abundance in Earth's crust
Abundance in Oceans
Abundance in Human Body
0 %
Abundance in Meteor
0 %
Abundance in Sun
0 %
Abundance in Universe
0 %

Nuclear Screening Constants