Cerium
Atomic Data
| Atomic Number | 58 |
| Symbol | Ce |
| Atomic Weight | 140.12 u |
| Density (STP) | 6.77 g/cm³ |
| Melting Point | 794.85 °C (1068 K) |
| Boiling Point | 3442.85 °C (3716 K) |
| Electronegativity | 1.12 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f1 5s2 5p6 5d1 6s2 |
| Oxidation States | +3, +4 |
| Phase at STP | Solid |
| Category | Lanthanoid |
| Period / Group | 6 / None |
| CAS Number | 7440-45-1 |
Electron Configuration
[Xe] 4f1 5d1 6s2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 1 | 47 |
| O | 5 | 5s | 2 | 49 |
| O | 5 | 5p | 6 | 55 |
| O | 5 | 5d | 1 | 56 |
| P | 6 | 6s | 2 | 58 |
| Total | 58 | 58 | ||
Isotopes of Cerium
Cerium has four naturally occurring stable isotopes. The most abundant is ¹⁴⁰Ce, comprising 88.45% of all naturally occurring Cerium.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Cerium-136 | ¹³⁶Ce | 58 | 78 | 0.185 | Stable |
| Cerium-138 | ¹³⁸Ce | 58 | 80 | 0.251 | Stable |
| Cerium-140 | ¹⁴⁰Ce | 58 | 82 | 88.45 | Stable |
| Cerium-142 | ¹⁴²Ce | 58 | 84 | 11.114 | Stable |
Abundance & Occurrence
Cerium is present in Earth's crust at approximately 66 ppm by mass and at approximately 1 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Universe (ppm by mass)
Discovery & History
Read more about the discovery of the periodic table of elements →
Safety & Handling
- Cerium oxide dust: CeO2 (ceria) nanoparticles and fine dust are respiratory irritants; nano-scale ceria has been shown in animal studies to cause pulmonary inflammation: use engineering controls and respiratory protection when handling fine ceria powder.
- Fire hazard: Cerium metal is pyrophoric when in fine particle form; filings and turnings can ignite spontaneously in air. Bulk cerium metal ignites in air above ~65 °C, earning it a place in lighter flints (mischmetal).
- Skin and eye contact: Cerium salts cause mild irritation to skin and eyes; soluble cerium compounds should be handled with gloves and eye protection.
- Cerium-144: radiation: Ce-144 (t½ = 285 days) is a fission product used in industrial radiography; it is a beta emitter and requires radiation protection protocols and shielded storage.
Cerium in the Real World
Real-World Uses
- Automotive catalytic converters: Cerium oxide (ceria, CeO₂) acts as an oxygen buffer in three-way catalytic converters, storing and releasing oxygen to maintain the stoichiometric exhaust mixture needed for simultaneous oxidation of CO and HC and reduction of NOx.
- Glass polishing: Cerium oxide powder is the premier precision polishing abrasive for optical glass, flat-panel display substrates, and semiconductor wafers; it removes material by a combined chemical-mechanical action that leaves surfaces optically flat.
- UV-blocking glass and self-cleaning ovens: Cerium oxide is added to glass to absorb ultraviolet radiation (used in UV-blocking sunglasses and automobile windscreens) and is a component of catalytic coatings in self-cleaning oven enamels.
- Lighter flints (misch metal): Misch metal, an unseparated rare-earth alloy that is approximately 50% cerium, produces sparks when struck against hardened steel, used in cigarette lighters, fire strikers, and tracer bullet compositions.
- Fuel additive: Cerium oxide nanoparticle fuel additives improve diesel combustion efficiency and reduce particulate emissions by acting as an oxidation catalyst within the combustion chamber.
Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.
Frequently Asked Questions
What is cerium used for?
Cerium's largest use is in catalytic converters: cerium oxide (ceria) stores and releases oxygen, helping the catalytic converter function over a wide range of air-fuel ratios. Ceria is also used as a glass polishing compound (cerium oxide powder polishes glass more efficiently than older rouge), in UV-absorbing glass, and in self-cleaning ovens (where ceria helps oxidise food residue at high temperatures). Cerium sulphide is an orange-red pigment.
Is cerium safe?
Cerium and its compounds are considered to have low to moderate toxicity. The metal ignites easily when scratched or heated, producing cerium oxide smoke that can cause respiratory irritation. Cerium is not considered carcinogenic or a cumulative toxin. Cerium compounds are handled routinely in industrial settings with standard precautions for metal dusts.
How was cerium discovered?
Cerium was discovered independently in 1803 by Swedish chemists Jöns Jacob Berzelius and Wilhelm Hisinger, and (separately) by German chemist Martin Heinrich Klaproth. Berzelius and Hisinger isolated it from the mineral cerite. It was named after the dwarf planet Ceres, which had been discovered just two years earlier in 1801, making cerium the first element named after a solar system body.
How does cerium oxide polish glass?
Cerium oxide is the most widely used glass polishing compound. Unlike abrasives that polish by mechanical scratching alone, ceria combines chemical and mechanical action: it reacts with silica at the glass surface in the presence of water, softening it chemically, while simultaneously providing mild mechanical abrasion. This dual mechanism gives ceria a faster cutting rate and better surface finish than pure abrasives like iron oxide, while being gentler and cheaper than diamond compounds.