Periodic Table > Europium
 

Terminology


Allotropes
Some elements exist in several different structural forms, these are called allotropes.


For more information on Murray Robertson’s image see Uses and properties facts below.

 

Fact box terminology


Group
Elements appear in columns or ‘groups’ in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.


Period
Elements are laid out into rows or ‘periods’ so that similar chemical behaviour is observed in columns.


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, principal, diffuse, and fundamental.


Atomic Number
The number of protons in the nucleus.


Atomic Radius/non -bonded (Å)
based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties, for more details please refer to the CRC Handbook of Chemistry and Physics.


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


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.


Melting Point (oC)
The temperature at which the solid-liquid phase change occurs.


Melting Point (K)
The temperature at which the solid-liquid phase change occurs.


Melting Point (oF)
The temperature at which the solid-liquid phase change occurs.


Boiling Point (oC)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (K)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (oF)
The temperature at which the liquid-gas phase change occurs.


Sublimation
Elements that do not possess a liquid phase at atmospheric pressure (1 atm) are described as going through a sublimation process.


Density (kgm-3)
Density is the weight of a substance that would fill 1 m3 (at 298 K unless otherwise stated).


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.


Key Isotopes (% abundance)
An element must by definition have a fixed number of protons in its nucleus, and as such has a fixed atomic number, however variants of an element can exist with differing numbers of neutrons, and hence a different atomic masses (e.g. 12C has 6 protons and 6 neutrons and 13C has 6 protons and 7 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 (where several isotopes exist, a value is presented for the most prevalent isotope).

Fact box

 
Group Lanthanides  Melting point 822 oC, 1511.6 oF, 1095.15 K 
Period Boiling point 1529 oC, 2784.2 oF, 1802.15 K 
Block Density (kg m-3) 5248 
Atomic number 63  Relative atomic mass 151.964  
State at room temperature Solid  Key isotopes 153Eu 
Electron configuration [Xe] 4f76s2  CAS number 7440-53-1 
ChemSpider ID 22417 ChemSpider is a free chemical structure database
 

Uses and properties terminology


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.


Natural Abundance

Where this element is most commonly found in nature.


Biological Roles

The elements role within the body of humans, animals and plants. Also functionality in medical advancements both today and years ago.


Appearance

The description of the element in its natural form.

Uses and properties

 
Image explanation
A design based on the European Union flag and monetary symbol.
Appearance
A soft, silvery metal that tarnishes quickly and reacts with water. It is used in making thin super-conducting alloys and in colour televisions.
Uses
Europium can absorb more neutrons per atom than any other element, making it valuable in control rods for nuclear reactors. Europium-doped plastic has been used as a laser material. Otherwise this element is very little used.
Biological role
Europium has no known biological role, and has low toxicity.
Natural abundance
In common with other lanthanides, europium is found principally in the minerals monazite and bastnaesite, from which it can be prepared. However, the usual method of preparation is by heating europium(Ill) oxide with an excess of lanthanum under vacuum.
 
Atomic data terminology

Atomic radius/non -bonded (Å)
Based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties,for more details please refer to the CRC Handbook of Chemistry and Physics.


Electron affinity (kJ mol-1)
The energy released when an additional electron is attached to the neutral atom and a negative ion is formed (where several isotopes exist, a value is presented for the most prevalent isotope). *


Electronegativity (Pauling scale)
The degree to which an atom attracts electrons towards itself, expressed on a relative scale as a function bond dissociation energies, Ed in eV. χA - χB =(eV)-1/2sqrt(Ed(AB)-[Ed(AA)+Ed(BB)]/2), with χH set as 2.2 (where several isotopes exist, a value is presented for the most prevalent isotope).


1st Ionisation energy (kJ mol-1)
The minimum energy required to remove an electron from a neutral atom in its ground state (where several isotopes exist, a value is presented for the most prevalent isotope).


Covalent radius (Å)
The size of the atom within a covalent bond, given for typical oxidation number and coordination (where several isotopes exist, a value is presented for the most prevalent isotope). ***

Atomic data

 
Atomic radius, non-bonded (Å) 2.350 Covalent radius (Å) 1.83
Electron affinity (kJ mol-1) 83.334 Electronegativity
(Pauling scale)
Unknown
Ionisation energies
(kJ mol-1)
 
1st
547.110
2nd
1085.459
3rd
2404.413
4th
4119.920
5th
-
6th
-
7th
-
8th
-
 

Mining/Sourcing Information

Data for this section of the data page has been provided by the British Geological Survey. To review the full report please click here or please look at their website here.


Key for numbers generated


Governance indicators

1 (low) = 0 to 2

2 (medium-low) = 3 to 4

3 (medium) = 5 to 6

4 (medium-high) = 7 to 8

5 (high) = 9


Reserve base distribution

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %

(Where data are unavailable an arbitrary score of 2 was allocated. For example, Be, As, Na, S, In, Cl, Ca and Ge are allocated a score of 2 since reserve base information is unavailable. Reserve base data are also unavailable for coal; however, reserve data for 2008 are available from the Energy Information Administration (EIA).)


Production Concentration

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %


Crustal Abundance

1 (low) = 100 to 1000 ppm

2 (medium-low) =10 to 100 ppm

3 (medium) = 1 to 10 ppm

4 (medium-high) = 0.1 to 1 ppm

5 (high) = 0.1 ppm

(Where data are unavailable an arbitrary score of 2 was allocated. For example, He is allocated a score of 2 since crustal abundance data is unavailable.)


Explanations for terminology


Crustal Abundance (ppm)

The abundance of an element in the Earth's crust in parts-per-million (ppm) i.e. The number of atoms of this element per 1 million atoms of crust.


Sourced

The country with the largest reserve base.


Reserve Base Distribution

This is a measure of the spread of future supplies, recording the percentage of a known resource likely to be available in the intermediate future (reserve base) located in the top three countries.


Production Concentrations

This reports the percentage of an element produced in the top three countries. The higher the value, the larger risk there is to supply.


Total Governance Factor

The World Bank produces a global percentile rank of political stability. The scoring system is given below, and the values for all three production countries were summed.


Relative Supply Risk Index

The Crustal Abundance, Reserve Base Distribution, Production Concentration and Governance Factor scores are summed and then divided by 2, to provide an overall Relative Supply Risk Index.

Supply risk

 
Scarcity factor 8.0
Country with largest reserve base China
Crustal abundance (ppm) 0.3
Leading producer China
Reserve base distribution (%) 59.30
Production concentration (%) 97.40
Total governance factor(production) 8
Top 3 countries (mined)
  • 1) China
  • 2) USA
  • 3) CIS
Top 3 countries (production)
  • 1) China
  • 2) Russia
  • 3) Brazil
 

Oxidation states and isotopes


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

Terminology


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. Free atoms have an oxidation state of 0, and the sum of oxidation numbers within a substance must equal the overall charge.


Important Oxidation states
The most common oxidation states of an element in its compounds.


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.

Oxidation states and isotopes

 
Common oxidation states 3, 2
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  151Eu 150.92 47.81 > 1.7x1018
  153Eu 152.921 52.19
 

Pressure and temperature - advanced terminology


Molar Heat Capacity (J mol-1 K-1)

Molar heat capacity is the energy required to heat a mole of a substance by 1 K.


Young's modulus (GPa)

Young's modulus is a measure of the stiffness of a substance, that is, 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 (GPa)

The shear modulus of a material is a measure of how difficult it is to deform a material, and is given by the ratio of the shear stress to the shear strain.


Bulk modulus (GPa)

The bulk modulus is a measure of how difficult to compress a substance. Given by the ratio of the pressure on a body to the fractional decrease in volume.


Vapour Pressure (Pa)

Vapour pressure is the 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

 
Molar heat capacity
(J mol-1 K-1)
27.66 Young's modulus (GPa) Unknown
Shear modulus (GPa) Unknown Bulk modulus (GPa) Unknown
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- 1.74
x 10-5
0.11 19.4 - - - - - - -
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History

Europium’s story is part of the complex history of the rare earths, aka lanthanoids. It began with cerium which was discovered in 1803. In 1839 Carl Mosander separated two other elements from it: lanthanum and one he called didymium which turned out to be a mixture of two rare earths, praseodymium and neodymium, as revealed by Karl Auer in 1879. Even so, it still harboured another rarer metal, samarium, separated by Paul-Émile Lecoq de Boisbaudran, and even that was impure. In 1886 Jean Charles Galissard de Marignac extracted gadolinium, from it, but that was still not the end of the story. In 1901, Eugène-Anatole Demarçay carried out a painstaking sequence of crystallisations of samarium magnesium nitrate, and separated yet another new element: europium.

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Podcasts

Listen to Europium Podcast
Transcript :

Chemistry in Its Element - Europium


  (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 uncovering the origins of the element that put red into colour TV and also spawned a row with France, so I suppose there's nothing unusual there.

Brian Clegg

Many countries are honoured in the periodic table. There's Americium, Germanium, Polonium, and Francium, to name but a few. Usually these place names reflect where their discoverer worked. But despite the number of elements first isolated in England - ten were found at the Royal Institution in London alone - there is no Englandium, Unitedkingdium or Brittanium. However, there is europium, which allows for the possibility of a UK discoverer. 

Europium is a lanthanide, one of those unfamiliar elements sitting outside the main structure of the periodic table. With atomic number 63, it inhabits the bar of elements that squeeze numerically between barium and hafnium. Along with scandium and [ITRIUM] yttrium, these are sometimes called rare earth elements - something of a misnomer, as they're not that scarce, but the minerals they were originally found in were rare, hence the name.

Europium wasn't so much discovered as groped towards. The British connection here is English scientist Sir William Crookes, who worked both in chemistry and physics. Crookes is probably best remembered for his work with discharge tubes. He was investigating (the scientific term for 'messing around with') the effect of putting a high voltage across two electrodes inside a tube with most of the air sucked out. This produced an unearthly glow on the glass at the end of the tube. Crookes called this effect a cathode ray. It was eventually shown to be caused by a stream of electrons, and the Crookes tube was the ancestor of traditional TV screens and computer monitors.

But Crookes was also an active chemist. He discovered the element thallium and is credited by some with the discovery of our topic today, europium. In the late 1880s, Crookes noticed a new line in spectroscopic analysis of a mineral containing ytterbium and samarium. Spectroscopy is a technique that makes it possible to analyze a material by measuring the different colours of light that are absorbed by it, or radiated when it's heated, giving a unique visual fingerprint. Crookes believed he had spotted a new element - so in a sense discovered europium, but never isolated it.

Others acknowledge French discoverers - either Paul Lecoq de [BOIS-BO-DRAN] Boisbaudran, a prolific investigator of new elements, who also identified a set of new lines a couple of years later, or definitively Eugene-Anatole Demarçay, who produced a europium salt in 1901 (it took many more years to get to the pure metal). It was certainly named by Demarçay - which should come as no surprise, as no Englishman of Crookes' time would think of himself as European.

This is a good example of the way that scientific discoveries aren't cut and dried. History-of-science expert Patricia Fara draws a parallel between the discoveries of europium and penicillin. We generally award the accolade for finding that life-saving mould to Alexander Fleming, who found it, but didn't pursue it further, rather than the team that isolated penicillin. But for europium, many historians play events the other way round, ignoring europium's Fleming, William Crookes.

Even if Crookes isn't the discoverer, he still plays a part in europium's story because of cathode ray tubes. If you are listening to this podcast on a computer with a traditional colour monitor, europium will be enhancing your view of the Chemistry World website. When colour TVs were first developed, the red pixels were relatively weak, which meant the whole colour spectrum had to be kept muted. But a phosphor doped with europium proved a much better, brighter source of red and is still present in most surviving monitors and TVs that predate the flat screen revolution.

Doping is something of a speciality for europium. Doping involves adding a relatively small amount of a material to another to change its properties. This is often europium's role in phosphors, the materials used to provide a glow when stimulated by electrons in TVs, or by ultraviolet in fluorescent lights. As well as the red glow from the valency three version of europium, its valency two salts produce a blue radiance. These are both combined with a third phosphor to produce white light in compact fluorescent bulbs.

Another phosphorescent role for europium, where the name is particularly apt, is as an anti-forgery mark on Euro bank notes. Europium is also behind the action of the mineral that gives us the word 'fluorescent'. In fluorescence, a material absorbs relatively high energy light such as ultraviolet and gives off a lower frequency in the visible range, making the substance unnaturally bright. The same type of europium responsible for the blue phosphor in fluorescent lights is present in some variants of the mineral fluorite, and it was its blue glow that resulted in the word fluorescent being derived from the mineral's name.

Although technically a metal, europium lacks the familiar metallic shininess because it oxidizes so easily. This silvery/white material is never naturally found in the free state. If it's not reacting with air, it fizzes away in water to produce a hydroxide. Europium is also a great neutron absorber, making it an interesting possibility for damping nuclear reactors by hoovering up stray neutrons, though it hasn't been widely used for this to date.

So that's europium - the substance that brings colours to phosphors. It's somehow rather appropriate that the discovery of europium, the element named after the continent of Europe, should be the subject of a dispute between England and France. Some things, it seems, will never change.

Chris Smith

Brian Clegg with the story of Europium, the element that makes you see red, or at least it does on an old fashioned TV screen.   Next week, the inside story on the element that just didn't want to be discovered.  

Chris Orvig

Vanadium, a first row transition metal in the Periodic Table, is an element of mystery.   Not only was it first transported two hundred years ago from Mexico, and lost in a shipwreck along with all of the relevant lab notes by the great German scientist Baron von Humboldt, but it required discovery several times by such famous names as Wöhler, Berzelius and del Rio (who was actually talked out of his claim in 1805).    

Chris Smith

But why, and who did eventually discover Vanadium and what do we do with it today.   To find out join Chris Orvig, on next week's Chemistry in its Element.   I'm Chris Smith, thank you for listening and goodbye. 

(Promo)

Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists dot com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld dot org forward slash elements.   

(End promo)

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References

 
Images:  Visual Elements © Murray Robertson 2011
Mining and Sourcing data:  British Geological Survey – natural environment research council.
Text:  John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Additional information for platinum, gold, neodymium and dysprosium obtained from Material Value Consultancy Ltd www.matvalue.com
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.