What is Cerium
Cerium (pronunciation: SER-ee-em) is a soft, grayish metal that belongs to the group of lanthanides and is represented by the chemical symbol Ce [1, 2]. Its naturally-occurring isotopes include Cerium-136, Cerium-138, Cerium-140, and Cerium-142, out of which Cerium-140 is the most abundant (with 88.48% natural abundance) . Among the 35 known radioisotopes of cerium, the most stable is Cerium-144 that is characterized by a half-life period of 284.893 days .
Where is Cerium Found
Cerium is commonly found in rare earth minerals like bastnaesite and monazite . The mineral ore is heated and then treated with hydrochloric acid to produce cerium oxide from which metallic cerium is isolated through electrochemical reduction . The metal can also be obtained through thermal reduction of cerium fluoride with calcium [1, 4]. While China, the CIS countries, and the USA have the highest cerium reserves, the top 3 cerium producing countries in the world are China, Russia, and Malaysia .
Origin of its Name: It is named after ‘Ceres’, an asteroid that was named after the Roman goddess of fertility and agriculture .
Who discovered it: The element was discovered by the Swedish chemists, Jöns Jacob Berzelius along with Wilhelm von Hisinger, and independently by the German chemist Martin Klaproth [1, 4].
When and How was it Discovered
In 1803, Berzelius and Hisinger discovered the new element from a reddish-brown cerium salt called cerite [1, 5]. While investigating the chemical reaction of the cerium salts, they found the two oxidation states – one of which producing yellowish-red salts and the other colorless ones . Although they did not isolate the pure form, they named the element ‘cerium’ and its oxide ‘ceria’ .
Martin Klaproth analyzed the salt and concluded that it consists of an oxide of a new metallic element . He named the oxide ‘ockroite’ because of its yellowish-red color . However, the result of Berzelius and Hisinger was published before that of Klaproth, and so the name cerium was approved .
|Atomic number||58 |
|CAS number||7440-45-1 |
|Position in the periodic table||Group||Period||Block|
|Lanthanides ||6 ||f |
Properties and Characteristics of Cerium
|Atomic mass||140.116 amu |
|Relative atomic mass||140.116 |
|Color||Gray [1, 5]|
|Melting point/freezing point||799 °C, 1470 °F |
|Boiling point||3443 °C, 6229 °F |
|Density||6.77 g cm-3 |
|State of matter at room temperature (solid/liquid/gas)||Solid [1, 5]|
|– Brinell||412 MPa |
|– Mohs||2.5 |
|– Vickers||270 MPa |
|Electrical conductivity||1.4X106 S/m |
|Thermal (heat) conductivity||11 W/(m K) |
|Specific heat||192 J kg-1 K-1 |
|Bulk modulus||21.5 GPa |
|Shear modulus||13.5 GPa |
|Young’s modulus||33.6 GPa |
|– Temperature (K)||400||600||800||1000||1200||1400||1600||1800||2000||2200||2400|
|– Pressure (Pa)||–||–||–||2.47 X 10-11||8.91 X 10-8||2.97 X 10-5||2.33 X 10-3||6.91 X 10-2||1.04||9.56||60.8|
|Oxidation state/Oxidation number||+2,+3, +4 |
|Isotopes||Isotope||Mass||Abundance (%)||Half-life||Mode of decay|
|136Ce||135.907||0.185||>0.7 X 1014 y||EC EC|
|>4.2 X 1015 y||β-β-|
|138Ce||137.906||0.251||>3.7 X 1014 y||EC EC|
|142Ce||141.909||11.114||>1.6 X 1017 y||β-β-|
Atomic Data of Cerium (Element 58)
|Valence electrons||2 |
|– n||4 |
|– ℓ||3 |
|– mℓ||-2 |
|– ms||+1/2 |
|Electron configuration (noble gas configuration)||[Xe] 4f15d16s2 |
|– Number of electrons||58 |
|– Number of neutrons||82 |
|– Number of protons||58 |
|Radius of Atom|
|– Atomic radius||2.42 Å |
|– Covalent radius||1.84 Å |
|Electronegativity (Pauling-scale)||1.12 |
|Electron affinity||62.72 kJ mol-1 |
|Ionization energy (kJ mol-1)||1st||2nd||3rd||4th||5th||6th||7th||8th|
What is It Used for
- The mischmetal alloy made of cerium, lanthanum, neodymium, and praseodymium mixed with magnesium oxide and iron oxide is used as flints for lighting cigarettes and gas [1, 5].
- Cerium oxide, as a catalyst, is used in self-cleaning ovens for preventing the accumulation of cooking residues and for polishing glass surfaces [1, 5].
- It is used in catalytic converters because it helps reduce automobile exhaust emissions . Cerium oxide nanoparticles are added to diesel for reducing the emission of soot and improving engine performance of vehicles .
- Cerium sulfide is non-toxic by nature and is used as a coloring pigment because of its rich red color .
- The element is used in phosphors in flat-screen televisions, floodlights, and energy-efficient light bulbs .
- Flammacerium, a compound containing cerium nitrate and silver sulfadiazine, is a topical ointment used for treating infections in burn wounds .
The element 58 has no known biological roles and is low to moderate in toxicity [1, 5].
- The image of cerium is a graphical representation of the asteroid Ceres, whereas the background is derived from an astronomical map of the 17th-century .
- Its natural abundance is almost similar to zinc, but it is more than lead or tin .
- At room temperature, the element can readily oxidize .
- Pure cerium may ignite if scratched with a sharp metal object such as a knife .
- It decomposes in water to produce cerium hydroxide and hydrogen .
Cost of Cerium
The cost of 100 grams of pure cerium is about $380, but in bulk, it is about $1.20 .
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