98 Cf 251

Californium

actinide

Properties

Atomic number
98
Atomic mass
251 u
Category
actinide
Group
f-block
Period
7
Block
f-block
State (room temp)
Solid
Outer-shell electrons
2
Electronegativity
1.3 (Pauling)
Density
15.1 g/cm³
Melting point
899.85 °C
Boiling point
1469.85 °C

Electron configuration

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁰

Noble-gas shorthand: [Rn] 5f¹⁰ 7s²

Electrons per shell: 2, 8, 18, 32, 28, 8, 2 — that's 2 in the outermost shell.

See how electron configuration is built →

Cf
Bohr model — outer-shell electrons in blue

About Californium

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).

Position in the periodic table

Open the interactive periodic table →

Data compiled from Wikipedia, PubChem, and IUPAC. Source.