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Oxidation & Electrons | Appearance & Characteristics Reactions | Compounds | Radius | Conductivity Abundance & Isotopes 
TEM image of a cerium oxide nanorod formed in an ice channel. (EMSL) |
General:
| Name: Cerium | Symbol: Ce |
| Type: Rare Earth, Lanthanide series | Atomic weight: 140.12 |
| Density @ 293 K: 6.78 g/cm3 | Atomic volume: 20.67 cm3/mol |
| Discovered: Cerium was discovered in Sweden by Jöns J. Berzelius and Wilhelm von Hisinger, and also independently in Germany by Martin Heinrich Klaproth, both in 1803. The element name comes from the asteroid Ceres, discovered two years earlier by Giuseppe Piazzi. | |
States
| State (s, l, g): solid | |
| Melting point: 1071 K (798 oC) | Boiling point: 3716 K (3443 oC) |
Energies
| Specific heat capacity: 0.19 J g-1 K-1 | Heat of atomization: 419 kJ mol-1 |
| Heat of fusion: 5.460 kJ mol-1 | Heat of vaporization : 398 kJ mol-1 |
| 1st ionization energy: 534.4 kJ mol-1 | 2nd ionization energy: 1050 kJ mol-1 |
| 3rd ionization energy: 1949 kJ mol-1 | Electron affinity: 50 kJ mol-1 |
Oxidation & Electrons
| Shells: 2,8,18,20,8,2 | Electron configuration: [Xe] 4f2 6s2 |
| Minimum oxidation number: 0 | Maximum oxidation number: 4 |
| Min. common oxidation no.: 0 | Max. common oxidation no.: 4 |
| Electronegativity (Pauling Scale): 1.12 | Polarizability volume: 29.6 Å3 |
Appearance & Characteristics
| Structure: fcc: face-centered cubic | Color: gray |
| Harmful effects: Cerium is considered to be moderately toxic. | Hardness: 2.5 mohs |
| Characteristics: Cerium is a reactive, soft, gray, lustrous metal that is malleable and ductile. It tarnishes in moist air and reacts with water to form cerium hydroxide plus hydrogen gas. Small particles of the metal may ignite if a knife scratches the pure metal surface. The metal is attacked by alkali solutions and all acids. Cerium has a variable electronic structure: the energy of the inner 4f level is nearly the same as that of the 6s level, allowing variable occupancy of these two levels. | |
| Uses: An alloy of cerium and lanthanum, with small amounts of neodymium and praseodymium (misch metal) combined with iron oxide and magnesium oxide is used as the flint in cigarette and gas lighters. Cerium is used in carbon-arc lighting, especially in the motion picture industry. Cerium oxide is used as a catalytic converter for automobiles and it is also used in the walls of self-cleaning ovens. | |
Reactions
| Reaction with air: vigorous, w/ht ⇒ CeO2 | Reaction with 6 M HCl: vigorous, ⇒ H2, CeCl3 |
| Reaction with 15 M HNO3: mild, ⇒ Ce(NO3)3 | Reaction with 6 M NaOH: |
Compounds
| Oxide(s): Ce2O3, CeO2 (ceria) | Chloride(s): CeCl3 |
| Hydride(s): CeH2, CeH3 |
Radius
| Atomic radius: 185 pm | Ionic radius (1+ ion): pm |
| Ionic radius (2+ ion): pm | Ionic radius (3+ ion): 115 pm |
| Ionic radius (2- ion): pm | Ionic radius (1- ion): pm |
Conductivity
| Thermal conductivity: 11.3 W m-1 K-1 | Electrical conductivity: 1.4 x 106 S m-1 |
Abundance & Isotopes
| Abundance earth's crust: 60 parts per million by weight, 8.9 parts per million by moles | |
| Abundance solar system: 4 parts per billion by weight, 30 parts per trillion by moles | |
| Cost, pure: $57 per 100g | |
| Cost, bulk: $57 per 100g | |
| Source: Cerium is the most abundant of the lanthanides. It is not found free in nature but is found in a number of minerals, mainly allanite, bastnasite and monazite. Commercially, cerium is prepared by electrolysis of the chloride or by reduction of the fused fluoride with calcium. | |
| Isotopes: Cerium has 30 isotopes whose half-lives are known, with mass numbers 123 to 152. Of these, three stable, 136Ce, 138Ce and 140Ce. The most abundant isotope is 140Ce at 88.5%. | |
