Periodic Table > Cerium
 

Glossary


Allotropes
Some elements exist in several different structural forms, called allotropes. Each allotrope has different physical properties.


For more information on the Visual Elements image see the Uses and properties section below.

 

Glossary


Group
A vertical column in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.


Period
A horizontal row in the periodic table. The atomic number of each element increases by one, reading from left to right.


Block
Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp (s), principal (p), diffuse (d), and fundamental (f).


Atomic number
The number of protons in an atom.


Electron configuration
The arrangements of electrons above the last (closed shell) noble gas.


Melting point
The temperature at which the solid–liquid phase change occurs.


Boiling point
The temperature at which the liquid–gas phase change occurs.


Sublimation
The transition of a substance directly from the solid to the gas phase without passing through a liquid phase.


Density (g cm−3)
Density is the mass of a substance that would fill 1 cm3 at room temperature.


Relative atomic mass
The mass of an atom relative to that of carbon-12. This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists, the value given is the abundance weighted average.


Isotopes
Atoms of the same element with different numbers of neutrons.


CAS number
The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems.


Fact box

 
Group Lanthanides  Melting point 799°C, 1470°F, 1072 K 
Period Boiling point 3443°C, 6229°F, 3716 K 
Block 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
 

Glossary


Image explanation

Murray Robertson is the artist behind the images which make up Visual Elements. This is where the artist explains his interpretation of the element and the science behind the picture.


Appearance

The description of the element in its natural form.


Biological role

The role of the element in humans, animals and plants.


Natural abundance

Where the element is most commonly found in nature, and how it is sourced commercially.

Uses and properties

 
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.
 
Glossary

Atomic radius, non-bonded
Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These values were determined using several different methods.


Covalent radius
Half of the distance between two atoms within a single covalent bond. Values are given for typical oxidation number and coordination.


Electron affinity
The energy released when an electron is added to the neutral atom and a negative ion is formed.


Electronegativity (Pauling scale)
The tendency of an atom to attract electrons towards itself, expressed on a relative scale.


First ionisation energy
The minimum energy required to remove an electron from a neutral atom in its ground state.

Atomic data

 
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
-
 

Glossary

Data for this section been provided by the British Geological Survey.


Relative supply risk

An integrated supply risk index from 1 (very low risk) to 10 (very high risk). This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores.


Crustal abundance (ppm)

The number of atoms of the element per 1 million atoms of the Earth’s crust.


Recycling rate

The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply.


Substitutability

The availability of suitable substitutes for a given commodity.
High = substitution not possible or very difficult.
Medium = substitution is possible but there may be an economic and/or performance impact
Low = substitution is possible with little or no economic and/or performance impact


Production concentration

The percentage of an element produced in the top producing country. The higher the value, the larger risk there is to supply.


Reserve distribution

The percentage of the world reserves located in the country with the largest reserves. The higher the value, the larger risk there is to supply.


Political stability of top producer

A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.


Political stability of top reserve holder

A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators.


Supply risk

 
Relative supply risk 9.5
Crustal abundance (ppm) 0.3
Recycling rate (%) <10
Substitutability High
Production concentration (%) 97
Reserve distribution (%) 50
Top 3 producers
  • 1) China
  • 2) Russia
  • 3) Malaysia
Top 3 reserve holders
  • 1) China
  • 2) CIS Countries (inc. Russia)
  • 3) USA
Political stability of top producer 24.1
Political stability of top reserve holder 24.1
 

Glossary


Common oxidation states

The oxidation state of an atom is a measure of the degree of oxidation of an atom. It is defined as being the charge that an atom would have if all bonds were ionic. Uncombined elements have an oxidation state of 0. The sum of the oxidation states within a compound or ion must equal the overall charge.


Isotopes

Atoms of the same element with different numbers of neutrons.


Key for isotopes


Half life
  y years
  d days
  h hours
  m minutes
  s seconds
Mode of decay
  α alpha particle emission
  β negative beta (electron) emission
  β+ positron emission
  EC orbital electron capture
  sf spontaneous fission
  ββ double beta emission
  ECEC double orbital electron capture

Oxidation states and isotopes

 
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 EC EC 
        > 4.2 x 1015 β- β- 
  138Ce 137.906 0.251 >3.7 x 1014 EC EC 
  140Ce 139.905 88.45
  142Ce 141.909 11.114 > 1.6 x 1017 β-β- 
 

Glossary


Specific heat capacity (J kg−1 K−1)

Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K.


Young's modulus

A measure of the stiffness of a substance. It provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain.


Shear modulus

A measure of how difficult it is to deform a material. It is given by the ratio of the shear stress to the shear strain.


Bulk modulus

A measure of how difficult it is to compress a substance. It is given by the ratio of the pressure on a body to the fractional decrease in volume.


Vapour pressure

A measure of the propensity of a substance to evaporate. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system.

Pressure and temperature data – advanced

 
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)
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
0.00233 0.0691 1.04 9.56 60.8
  Help text not available for this section currently

History

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.
  Help text not available for this section currently

Podcasts

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)
  Help text not available for this section currently
  Help Text

Resources

Description :
This is an introduction and overview to five Commerical Skills Modules for Chemists. It includes a briefing for students, presentation video, an overview guide and presentation for tutors and market r...
Description :
This module asks teams of students to evaluate a number of potential projects, with a chemical background, and identify why they might be of potential value. This resource provides all the information...
Description :
This module asks teams of students to identify the route to market, and produce a ‘project plan’, for a number of potential projects with a chemical background. This resource contains a Tutor Guide an...
Description :
In this module students are asked to summarise and critique two out of the five chemistry-based projects, based on their previous work, and present their preferred option to a "business" audience.  Th...
Description :
This module asks teams of students to estimate the market value of a number of potential projects with a chemical background. This resource contains all the information necessary to run the Market Res...
Description :
This module asks teams of students to assess the financial impacts of two projects with a chemical background. This resource provides all the information necessary to run the Finance module.  It conta...
 

Terms & Conditions


Images © Murray Robertson 1999-2011
Text © The Royal Society of Chemistry 1999-2011

Welcome to "A Visual Interpretation of The Table of Elements", the most striking version of the periodic table on the web. This Site has been carefully prepared for your visit, and we ask you to honour and agree to the following terms and conditions when using this Site.


Copyright of and ownership in the Images reside with Murray Robertson. The RSC has been granted the sole and exclusive right and licence to produce, publish and further license the Images.


The RSC maintains this Site for your information, education, communication, and personal entertainment. You may browse, download or print out one copy of the material displayed on the Site for your personal, non-commercial, non-public use, but you must retain all copyright and other proprietary notices contained on the materials. You may not further copy, alter, distribute or otherwise use any of the materials from this Site without the advance, written consent of the RSC. The images may not be posted on any website, shared in any disc library, image storage mechanism, network system or similar arrangement. Pornographic, defamatory, libellous, scandalous, fraudulent, immoral, infringing or otherwise unlawful use of the Images is, of course, prohibited.


If you wish to use the Images in a manner not permitted by these terms and conditions please contact the Publishing Services Department by email. If you are in any doubt, please ask.


Commercial use of the Images will be charged at a rate based on the particular use, prices on application. In such cases we would ask you to sign a Visual Elements licence agreement, tailored to the specific use you propose.


The RSC makes no representations whatsoever about the suitability of the information contained in the documents and related graphics published on this Site for any purpose. All such documents and related graphics are provided "as is" without any representation or endorsement made and warranty of any kind, whether expressed or implied, including but not limited to the implied warranties of fitness for a particular purpose, non-infringement, compatibility, security and accuracy.


In no event shall the RSC be liable for any damages including, without limitation, indirect or consequential damages, or any damages whatsoever arising from use or loss of use, data or profits, whether in action of contract, negligence or other tortious action, arising out of or in connection with the use of the material available from this Site. Nor shall the RSC be in any event liable for any damage to your computer equipment or software which may occur on account of your access to or use of the Site, or your downloading of materials, data, text, software, or images from the Site, whether caused by a virus, bug or otherwise.


We hope that you enjoy your visit to this Site. We welcome your feedback.

References

 
Visual Elements images and videos
© Murray Robertson 2011.

 

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 3.0), 2010, National Institute of Standards and Technology, Gaithersburg, MD, accessed December 2014.
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

© John Emsley 2012.

 

Podcasts

Produced by The Naked Scientists.

 

Periodic Table of Videos

Created by video journalist Brady Haran working with chemists at The University of Nottingham.
  • LearnChemistry
  • Download our free Periodic Table app for mobile phones and tablets now.
  • Google play
  • App Store