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.



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

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

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.

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.

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 1412°C, 2574°F, 1685 K 
Period Boiling point 2567°C, 4653°F, 2840 K 
Block Density (g cm−3) 8.55 
Atomic number 66  Relative atomic mass 162.500  
State at 20°C Solid  Key isotopes 164Dy 
Electron configuration [Xe] 4f106s2  CAS number 7429-91-6 
ChemSpider ID 22355 ChemSpider is a free chemical structure database


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.


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 a stylised depiction of a nuclear reactor, reflecting the use of the element in reactor control rods.
A bright, silvery metallic element.
As a pure metal it is little used, because it reacts readily with water and air. Dysprosium’s main use is in alloys for neodymium-based magnets. This is because it is resistant to demagnetisation at high temperatures. This property is important for magnets used in motors or generators. These magnets are used in wind turbines and electrical vehicles, so demand for dysprosium is growing rapidly.

Dysprosium iodide is used in halide discharge lamps. The salt enables the lamps to give out a very intense white light.

A dysprosium oxide-nickel cermet (a composite material of ceramic and metal) is used in nuclear reactor control rods. It readily absorbs neutrons, and does not swell or contract when bombarded with neutrons for long periods.
Biological role
Dysprosium has no known biological role. It has low toxicity.
Natural abundance
In common with many other lanthanides, dysprosium is found in the minerals monazite and bastnaesite. It is also found in smaller quantities in several other minerals such as xenotime and fergusonite.

It can be extracted from these minerals by ion exchange and solvent extraction. It can also be prepared by the reduction of dysprosium trifluoride with calcium metal.
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Dysprosium was discovered in 1886 by Paul-Émile Lecoq de Boisbaudran in Paris. Its discovery came as a result of research into yttrium oxide, first made in 1794, and from which other rare earths (aka lanthanoids) were subsequently to be extracted, namely erbium in 1843, then holmium in 1878, and finally dysprosium. De Boisbaudran’s method had involved endless precipitations carried out on the marble slab of his fireplace at home.

Pure samples of dysprosium were not available until Frank Spedding and co-workers at Iowa State University developed the technique of ion-exchange chromatography around 1950. From then on it was possible to separate the rare earth elements in a reliable and efficient manner, although that method of separation has now been superseded by liquid-liquid exchange technology.

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) 2.31 Covalent radius (Å) 1.80
Electron affinity (kJ mol−1) Unknown Electronegativity
(Pauling scale)
Ionisation energies
(kJ mol−1)


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.


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 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  156Dy 155.924 0.056
  158Dy 157.924 0.095
  160Dy 159.925 2.329
  161Dy 160.927 18.889
  162Dy 161.927 25.475
  163Dy 162.929 24.896
  164Dy 163.929 28.26


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.


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


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)
173 Young's modulus (GPa) 61.4
Shear modulus (GPa) 24.7 Bulk modulus (GPa) 40.5
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - 1.54
x 10-8
x 10-5
0.0241 1.362 27.5 - - - -
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Listen to Dysprosium Podcast
Transcript :

Chemistry in its element: dysprosium


You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry.

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Meera Senthilingam

This week an element which played hard to get but once caught gave a wide range of chemical applications. Simon Cotton.

Simon Cotton

If you study a timeline of the discovery of the chemical elements, you see that new elements have often been discovered in clusters, in parallel with some other breakthrough in science. Obviously, the transuranium elements were a spin-off from developments in radiochemistry accompanying the Manhattan project - the second world war project to develop the first atomic bomb. Likewise the noble gases could easily be separated once cryogenics became feasible, thanks to the invention of Dewar's flask.

In the mid-19th century, Bunsen and Kirchhoff found that different elements emitted light of different frequencies when hot, and used this to identify new elements such as rubidium and caesium. Paul Émile Lecoq de Boisbaudran was one of the first people to exploit this new technique. He came from Cognac in France, so you will not be surprised to learn that his family made cognac. In 1875, he identified gallium from two spectroscopic lines in the spectrum of a sample of zinc blende from the Pyrénées, and isolated the element later that year, thus filling one of the gaps left in the Periodic Table by Mendeleev. At that time, scientists were using improved techniques such as fractional crystallisation to obtain the individual lanthanides from mixtures. In 1879 Lecoq went on to extract pure samarium from the mineral samarskite whilst in 1886 he was the first person to identify dysprosium by separating its oxide from holmium oxide. To achieve the separation, he used precipitations with ammonia and with oxalate, checking the fractions spectroscopically. It took him over 30 goes to do this, so he named the element accordingly, from the Greek word, dysprositos, meaning "hard to get at".

All the lanthanides are rather similar to each other chemically, showing gradations in properties from one end of the series to the other, but electronic and magnetic properties which depend upon the number of electrons, vary a lot from one lanthanide to its neighbour, giving each lanthanide its own particular uses.

One very unusual application for dysprosium is in the alloy Terfenol-D, which also contains terbium and iron. It is a magnetostrictive material, meaning that when it is put into a magnetic field, it changes shape, reversibly. This has found applications in ships' sonar systems (underwater radar using soundwaves) and in all sorts of sensors and transducers.

Along with a little caesium iodide and mercury bromide, dysprosium iodide is used in Medium Source Rare Earth Lamps (otherwise known as MSRs). These are discharge lamps where the dysprosium iodide emits over a range of frequencies, giving a good colour rendering. Caesium iodide helps broaden the emission whilst the mercury bromide reduces corrosion of the bulb and of the tungsten electrodes. These have applications including the film industry; the lamps have a high luminous efficiency whilst they can be dimmed appreciably whilst still maintaining the same "colour temperature".

Like other heavier lanthanides, dysprosium has a lot of unpaired electrons, giving both the metal and its ions a high magnetic susceptibility. This has led to applications in data storage devices, such as compact discs.

Dysprosium has a high thermal neutron absorption cross-section, meaning that it is very good at absorbing neutrons. Because of this, it is used to make the control rods that are put into nuclear reactors to absorb excess neutrons and stop fission reactions getting out of control.

There seem to be a lot of dys- words around at the start of the 21st century, They have the Greek prefix for abnormal or bad - dyslexic, dyspepsia and dysfunctional spring to mind. Dysprosium's not like that, it has many applications and as time goes on it will have even more.

Meera Senthilingam

So elementally changing the connotations of the greek prefix. That was Simon Cotton explaining the widely applied chemistry of dysprosium. Now next week, a mythological element that appears to be weeping.

Jon Steed

The element was christened after Niobe the daughter of Tantalus in greek mythology. Niobe had a fairly hard time of it. She was foolish enough to suggest that rather than worshipping invisible gods, it might be a nice idea to appreciate real people for a change. The greek gods weren't very forgiving of this kind of hubris and as a punishment killed if not all then most of her twelve children - the Niobids. As a result Niobe fled to mount Sipylus and was turned to stone. There is to this day a rock formation in the Aegean region of Turkey termed the weeping rock that resembles a woman's face purportably Niobe's. Water seeps through the porous limestone of the weeping rock and is said to resemble Niobe's unceasing tears at the fate of the Niobids.

Meera Senthilingam

And move away from the tears to find out the colourful and superconducting chemistry of the element niobium with Jon Steed in next week's Chemistry in its Element. Until then I'm Meera Senthilingam, thanks for listening and goodbye.


Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by There's more information and other episodes of Chemistry in its element on our website at

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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.


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.



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