Atomic number:58

Group numbers:3

Period:6

Electronic configuration:[Xe] 4f² 6s²

Formal oxidation number:+3 +4

Electronegativities:1.12

Atomic radius / pm:182.5

Relative atomic mass:140.116 ± 0.001

 

Cerium was discovered by Jöns Jakob Berzelius and Wilhelm Hisinger (SE) in 1803 and independently by Martin Heinrich Klaproth (DE). Named after the asteroid Ceres discovered two years before the element. It is a malleable, ductile, iron-grey metal that tarnishes in air and reacts easily with water. Cerium dissolves in acids and ignites when heated. Metal ignites and burns readily. Strong reductant. Cerium is most abundant rare earth metal. Found in many minerals like monazite sand [Ce(PO4)]. Its oxides are used in the optics and glass-making industries. Its salts are used in the photography and textile industry. Cerium is also used in high-intensity carbon lamps and as alloying agents in special metals.

Density / g dm^-3:8240 (alpha, 298 K)

 6749 (beta, 298 K)

 6773 (gamma, 298 K)

Molar volume / cm³mol^-1:17.00 (alpha, 298 K)

 20.76 (beta, 298 K)

 20.69 (gamma, 298 K)

Electrical resistivity / μΩcm:75 (20 °C)

Thermal conductivity / W m^-1K^-1:11.4

Melting point / °C:798

Boiling point / °C:3443

Heat of fusion / kJ mol^-1:8.87

Heat of vaporization / kJ mol^-1:398

Heat of atomization / kJ mol^-1:423.4

1st ionization energy / kJ mol^-1:534.41

2nd ionization energy / kJ mol^-1:1046.87

3rd ionization energy / kJ mol^-1:1948.82

in the atmosphere / ppm:-

in the Earth's crust / ppm:33

in the oceans / ppm:0.0004