Californium
Element 98 on the periodic table, symbol Cf, group 3, period 7.
Californium 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).
Appearance: silvery
Properties
- Atomic Number
- 98
- Atomic Mass
- 251.0000 u
- Group
- 3
- Period
- 7
- Block
- f-block
- Category
- Actinide
- State at 25 °C
- Solid
- Melting Point
- 1,173 K · 899.9 °C
- Boiling Point
- 1,743 K · 1,469.9 °C
- Density
- 15.1 g/cm³
- Atomic Radius
- Not measured
- Electronegativity
- 1.3
- Oxidation States
- +3
- Abundance in Crust
- Vanishingly rare
- Discovered
- 1950
- Discovered By
- Lawrence Berkeley National Laboratory
Electron Configuration
[Rn] 5f10 7s2
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f10
Ionisation Energies (kJ/mol)
- 1. 608
Elements near Californium
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.