| Discovery date | 1803 |
| Discovered by | Jöns Jacob Berzelius and Wilhelm Hisinger |
| Origin of the name | Cerium is named for the asteroid, Ceres, which in turn was named after the Roman goddess of agriculture. |
| Allotropes | - |
Ce
Cerium
58
140.116
| Group | Lanthanides | Melting point | 799°C, 1470°F, 1072 K |
| Period | 6 | Boiling point | 3443°C, 6229°F, 3716 K |
| Block | f | Density (g cm−3) | 6.77 |
| Atomic number | 58 | Relative atomic mass | 140.116 |
| State at 20°C | Solid | Key isotopes | 140Ce |
| Electron configuration | [Xe] 4f15d16s2 | CAS number | 7440-45-1 |
| ChemSpider ID | 22411 | ChemSpider is a free chemical structure database | |
Image explanation
The image is based on the asteroid Ceres, after which the element is named. The background is based on an early 17th-century astronomical map.
Appearance
Cerium is a grey metal. It is little used because it tarnishes easily, reacts with water and burns when heated.
Uses
Cerium is the major component of mischmetal alloy (just under 50%). The best-known use for this alloy is in ‘flints’ for cigarette lighters. This is because cerium will make sparks when struck. The only other element that does this is iron.
Cerium(Ill) oxide has uses as a catalyst. It is used in the inside walls of self-cleaning ovens to prevent the build-up of cooking residues. It is also used in catalytic converters. Cerium(III) oxide nanoparticles are being studied as an additive for diesel fuel to help it burn more completely and reduce exhaust emissions.
Cerium sulfide is a non-toxic compound that is a rich red colour. It is used as a pigment.
Cerium is also used in flat-screen TVs, low-energy light bulbs and floodlights.
Biological role
Cerium has no known biological role.
Natural abundance
Cerium is the most abundant of the lanthanides. It is more abundant than tin or lead and almost as abundant as zinc. It is found in a various minerals, the most common being bastnaesite and monazite.
Cerium oxide is produced by heating bastnaesite ore, and treating with hydrochloric acid. Metallic cerium can be obtained by heating cerium(III) fluoride with calcium, or by the electrolysis of molten cerium oxide.
Cerium was first identified by the Jöns Berzelius and Wilhelm Hisinger in the winter of 1803/4. Martin Klaproth independently discovered it around the same time.
Although cerium is one of the 14 lanthanoid (aka rare earth) elements it was discovered independently of them. There are some minerals that are almost exclusively cerium salts such as cerite, which is cerium silicate. A lump of this mineral had been found in 1751 by Axel Cronstedt at a mine in Vestmanland, Sweden. He sent some to Carl Scheele to analyse it but he failed to realise it was new element. In 1803, Berzelius and Hisinger examined it themselves and proved that it contained a new element.
It was not until 1875 that William Hillebrand and Thomas Norton obtained a pure specimen of cerium itself, by passing an electric current through the molten cerium chloride.
| Atomic radius, non-bonded (Å) | 2.42 | Covalent radius (Å) | 1.84 |
| Electron affinity (kJ mol−1) | 62.72 |
Electronegativity (Pauling scale) |
1.12 |
|
Ionisation energies (kJ mol−1) |
1st
534.403
2nd
1046.87
3rd
1948.811
4th
3546.608
5th
6324.61
6th
7487.3
7th
-
8th
-
|
||
| Common oxidation states | 4, 3 | ||||
| Isotopes | Isotope | Atomic mass | Natural 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 | |
| 140Ce | 139.905 | 88.45 | - | - | |
| 142Ce | 141.909 | 11.114 | > 1.6 x 1017 y | β-β- | |
|
|
|
Specific heat capacity (J kg−1 K−1) |
192 | Young's modulus (GPa) | 33.6 | |||||||||||
| Shear modulus (GPa) | 13.5 | Bulk modulus (GPa) | 21.5 | |||||||||||
| Vapour pressure | ||||||||||||||
| Temperature (K) |
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| Pressure (Pa) |
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| Listen to Cerium Podcast |
|
Transcript :
Chemistry in its element: cerium(Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello, this week we're meeting the chemical that behaves badly and won't obey the rules when it comes to compounds involving oxygen and if that wasn't inflammatory enough, it is also the source of sparks that brings a lighter to life. But thankfully it's also got a softer side and that is a soothing remedy for burns, as Andrea Sella knows only too well. Andrea Sella A few weeks ago I had a stupid accident in the lab; I wont go into the details; I am not terribly proud about what happened. But the result is I suffered from some superficial burns on my face and neck. I was seen to by a specialist nurse who nodded at me and then handed me tub of ointment. 'Its flammacerium', she said, 'apply it twice a day'. 'Flama what', I replied, 'cerium', she said. I was delighted. 'Cerium, it can not be serious, it's my favorite element'. The nurse laughed. Fortunately she didn't ask me why, she would have never got me out of the clinic. But perhaps if she listened to this Podcast, she will find out. Cerium is one of the first members of a series of about 14 elements with exotic and evocative names often referred to as the 'rare earths' or 'lanthanides'. The most striking thing about these elements is their remarkable chemical similarity. So much so for almost a hundred years, chemists almost went mad trying to separate them. William Crookes, the great Victorian inventor and spectroscopist wrote in 1887, 'these elements perplex us in our researches; they baffle us in our speculations and haunt us in our very dreams. They stretch like an unknown sea before us marking mystifying and murmuring strange revelations and possibilities'. Yet Cerium stands out from the crowd with its insoluble ceramic oxide, Ceria which has changed our world. But I'm, getting ahead of myself. The discovery of cerium was an accident. Around 1800, a young geologist Wilhelm Hisinger was rock hunting on his father's estate on the island of Västmanland, in Sweden, and found a new mineral that struck him as unusually dense. Hoping that it might be an ore of the recently discovered element Tungsten, Hisinger sent a sample to that element's discoverer Carl Wilhelm Scheele who took a look and said rather unhelpfully that there was no Tungsten in it. Undeterred Hisinger went to work with the great Swedish analytical chemist theorist Jöns Jakob Berzelius. In 1803, they isolated a new metallic element that they separated, thanks to the insolubility of its oxide. The named the element after the asteroid Ceres, itself named after the Roman goddess of agriculture. At about the same time, the German analyst Martin Klaproth isolated the same element from a different Scandinavian mineral. Both reports appeared in the same journal a few months apart causing something of an academic clash over exactly who got there first. The isolation of the metal however would have to wait another 70 years until the electrolysis of molten cerium chloride. The metal itself is nothing special to look at; it's a standard silver grey color and it tarnishes slowly in air as an oxide layer builds up on the surface. But in powdered form it is much more exciting. It is highly reactive particularly when alloyed with iron; it forms a brittle material ferrous cerium which sparks spectacularly when struck and is the basis of the flints of cigarette lighters and those exciting fire steels for chefs. Why does it burn so furiously? Well Cerium is fairly electro positive. So it will give up its outer electrons easily. And the oxide Ceria that I alluded to earlier is almost brick like in its stability. So it gives out huge amount of energies when it combusts. Ceria is also very hard which has made it a useful roche or polish for lens. If you happen to want to grind or polish your own telescope, then cerium dioxide is probably what you will use. But what makes the oxide really interesting is it misbehaves. Although the formula may appear to be CeO2, one cerium 2 oxygens in reality the compound always has slightly less than 2 oxygens; the surface is peppered with defects, gaps where an oxygen atom should be and the degree of imperfection varies; it depends very much on how the oxide is prepared or treated. So one of the headline uses for this apparently flawed oxide is in the catalytic converters of cars and trucks. A honeycomb of cerium dioxide helps to combust un-burnt fuel coming down the exhaust pipe by releasing oxygen during the oxygen lean part of the engine's cycle while picking the oxygen back up in the rich stage. As a nanopowder, mixed in with diesel fuel, it can clean up the otherwise sooty fumes produced by trucks and buses. So Cerium is critical for reducing the impact of the internal combustion engines that power our vehicles. But if you take an even closer look at Ceria it becomes more confusing. At first sight it looks like a no-brainer. Cerium looses 4 electrons handing them over to the surrounding oxygen leaving aside defects, this means it has a 4+ oxidation state. But on very close inspection with x-ray spectroscopy its clear that the cerium hangs on to at least some of those four electrons and its true oxidation state is in a quantum mechanical limbo some where between 3 and 4. Indeed the great Japanese spectroscopist Akio Kotani once wrote that 'there is no genuine example of Cerium 4'. And as always there is mystery concealed just beneath the surface of even the most apparently simple looking chemistry. So why you might ask, is cerium a burn cream; that too is a mystery. The most that the doctors can tell me is that it seems to work. Something to which I can great fully attest. Chris Smith That's UCL's Andrea Sella on cerium the element that sparks up lighters, vanishes burns and also helps us to clean up our act when it comes to pollution. Now next week it's definitely a case of don't blink, or you might miss it. Phillip Ball The nuclear collisions used to make them created only about one atom per hour. Yet 7 fleeting atoms of seaborgium to work with, the researches figured out that it's a metal comparable to molybdenum and tungsten. In such virtuoso experiments we can see the periodic table continuing to exert its pattern even among the elements that nature never glimpsed. Chris Smith And Phil Ball will be telling us the story of those 7 atoms of seaborgium next time. I do hope you can join us. I'm Chris Smith, thanks for listening. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements. (End promo)
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Visual Elements images and videos
© Murray Robertson 1998-2017.
W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.
John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.
Derived in part from material provided by the British Geological Survey © NERC.
Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.
Produced by The Naked Scientists.
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
© Murray Robertson 1998-2017.
Data
W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.
Uses and properties
John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.
Supply risk data
Derived in part from material provided by the British Geological Survey © NERC.
History text
Elements 1-112, 114, 116 and 117 © John Emsley 2012. Elements 113, 115, 117 and 118 © Royal Society of Chemistry 2017.
Podcasts
Produced by The Naked Scientists.
Periodic Table of Videos
Created by video journalist Brady Haran working with chemists at The University of Nottingham.
