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98Cf251.000
Californium
ActinideCalifornium is a radioactive metallic chemical element with symbol Cf and atomic number 98. The element was first made in 1950 at the University of California Radiation Laboratory in Berkeley, by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium).
Phase: SolidAppearance: silvery
2, 8, 18, 32, 28, 8, 2
Physical Properties
Atomic Mass251 u
Density15.1 g/cm³
Melting Point1173 K
Boiling Point1743 K
Period7
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f10
Semantic Config[Rn] 5f10 7s2
Shells2, 8, 18, 32, 28, 8, 2
Electron Affinity-97.31 kJ/mol
Electronegativity1.3
Ionization Energies
IE1: 608 kJ/mol
Discovery
Discovered byLawrence Berkeley National Laboratory