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 Melting point 1522°C, 2772°F, 1795 K 
Period Boiling point 3345°C, 6053°F, 3618 K 
Block Density (g cm−3) 4.47 
Atomic number 39  Relative atomic mass 88.906  
State at 20°C Solid  Key isotopes 89
Electron configuration [Kr] 4d15s2  CAS number 7440-65-5 
ChemSpider ID 22429 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 radar reflects the use of yttrium in radar technology. The element also used to provide the red colour for early colour television screens, and this is the reason for the background which echoes the Warner Bros. ‘That’s all Folks!’ cartoon splash screen.
A soft, silvery metal.
Yttrium is often used as an additive in alloys. It increases the strength of aluminium and magnesium alloys. It is also used in the making of microwave filters for radar and has been used as a catalyst in ethene polymerisation.

Yttrium-aluminium garnet (YAG) is used in lasers that can cut through metals. It is also used in white LED lights.

Yttrium oxide is added to the glass used to make camera lenses to make them heat and shock resistant. It is also used to make superconductors. Yttrium oxysulfide used to be widely used to produce red phosphors for old-style colour television tubes.

The radioactive isotope yttrium-90 has medical uses. It can be used to treat some cancers, such as liver cancer.
Biological role
Yttrium has no known biological role. Its soluble salts are mildly toxic.
Natural abundance
Xenotime can contain up to 50% yttrium phosphate. It is mined in China and Malaysia. Yttrium also occurs in the other ‘rare earth’ minerals, monazite and bastnaesite. Yttrium metal is produced by reducing yttrium fluoride with calcium metal.
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In 1787, Karl Arrhenius came across an unusual black rock in an old quarry at Ytterby, near Stockholm. He thought he had found a new tungsten mineral, and passed the specimen over to Johan Gadolin based in Finland. In 1794, Gadolin announced that it contained a new 'earth' which made up 38 per cent of its weight. It was called an’ earth’ because it was yttrium oxide, Y2O3, which could not be reduced further by heating with charcoal.

The metal itself was first isolated in 1828 by Friedrich Wöhler and made by reacting yttrium chloride with potassium. Yet, yttrium was still hiding other elements.

In 1843, Carl Mosander investigated yttrium oxide more thoroughly and found that it consisted of three oxides: yttrium oxide, which was white; terbium oxide, which was yellow; and erbium oxide, which was rose-coloured.

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) 2.32 Covalent radius (Å) 1.76
Electron affinity (kJ mol−1) 29.621 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
  89Y 88.906 100


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) 33
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)
298 Young's modulus (GPa) 63.5
Shear modulus (GPa) 25.6 Bulk modulus (GPa) 41.2
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - - 6.66
x 10-11
x 10-7
0.000117 0.0102 0.316 4.27 35.9 -
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Listen to Yttrium Podcast
Transcript :

Chemistry in its element: yttrium


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

(End promo)

Meera Senthilingam

This week, the last of the elements discovered in the small town of Ytterby and its compounds appear to have a multitude of uses.

Simon Cotton

Y. This is not a question. Y is the symbol for the element yttrium.

Until about 20 years ago, most scientists had not heard of it, other than vaguely noting where it was in the periodic table, under scandium and above lanthanum. Some people might just have known that it was one of 4 chemical elements named after the small Swedish town of Ytterby, along with ytterbium, erbium and terbium.

Then in 1986 two scientists working at IBM in Zurich, Georg Bednorz and Karl Müller, found that lanthanum barium copper oxide became superconducting at what was then almost a record high temperature, 35 degrees above absolute zero. In other words, below minus 238°C the compound's electrical resistance disappeared.

Bednorz and Müller won the Nobel Prize for Physics in 1987 for this discovery. Prompting other scientists to dust off their Periodic Tables, and try switching the lanthanum portion for other similar metals. Two American professors, Maw-Kuen Wu and Paul Chu, together with their research groups at the University's of Alabama and Houston, studied yttrium barium copper oxide. It has the formulaYBa2Cu3O7 and is often called YBCO for short. They found that it became superconducting 95 degrees below absolute zero (-178 ºC).

This may not seem much of a temperature difference, but it meant that YBCO could be kept in the superconducting state using liquid nitrogen, rather than the much more expensive liquid helium. This has inspired lots more studies over the past 20 years. The ultimate objective, the Holy Grail, is to find a material that would superconduct at room temperature, but no one has got there yet.

There are many possible applications for YBCO; for example MRI scanners could be made to operate more cheaply at a higher temperature using liquid nitrogen coolant. At present, though, there are technical problems preventing these commercial applications. One is that in order to superconduct at 95K, the YBCO has to be slightly oxygen-deficient, to have just a bit less than the seven oxygen atoms per yttrium atom. The exact amount is crucial, and tricky to achieve.

Other problems include making the YBCO in the right state; a lot of research is going into making thin films of it and finding a way of making it into a continuous wire, rather than just an assembly of crystals packed together that are unable to conduct decent currents. Investigators are looking into depositing YBCO on top of flexible metal wires, and research into this continues.

Apart from this, there are lots of everyday applications for yttrium compounds In its compounds yttrium is always present as the yttrium three plus ion, which means that it is colourless and has no unpaired electrons; therefore it does not have any interesting magnetic or spectroscopic properties of its own. The up side of this is that yttrium compounds make very good host materials for other lanthanides.

The most familiar application lies in the red phosphor in cathode ray tubes, as used in traditional colour TV sets. This is made of yttrium oxysulphide, Y2O2S containing a small amount of trivalent europium ions. Similarly, yttrium hosts are often used to accommodate terbium ions, which are green phosphors. Such materials are used in the "cool white" fluorescent lamps.

Yttrium aluminium garnet, also known as YAG, is a very important synthetic mineral. It is used to make hard, artificial diamonds, which sparkle just like the real ones. What is more, by introducing small quantities of lanthanide ions, materials with a range of useful properties can be made. Introduce a small amount of cerium for example, and you have a good yellow phosphor. Or add 1 % of neodymium to YAG and you get the most widely used solid-state laser material. And erbium gives you an infrared laser.

Yttrium also finds use in fuel cells for powering cars and buses, computers and digital phones and, potentially, buildings. A small amount of yttrium oxide is added to zirconium oxide to make what is known as yttria-stabilized zirconia (also called YSZ). That has the unusual property of conducting oxide ions, making it very useful in these fuel cells. YSZ is also used to make the lambda sensors fitted to the exhaust sytem of your car. These monitor the amount of oxygen in the exhaust gases and sends feedback to give the best air-fuel mixture into the engine.

So, that is yttrium for you. Colourless, unspectacular, but undoubtedly fulfilling a lot of important supporting roles.

Meera Senthilingam

And so the Oscar for best supporting role goes to, you guessed it, Yttrium. That was Uppingham School's Simon Cotton with the multiple roles and uses of Yttrium. Now next week we've got an element that could take us into another dimension.

Hayley Birch

In 1949, Milton Smith published a short work of fiction that he entitled The Mystery of Element 117. The real element 117 is yet to be discovered - it's a blank space in the Periodic Table just below the halogens. Smith's 117, however, was a strange material that could be used to open a window to another dimension. He called it a magnetic monopole substance - one that instead of having poles, plural, like an ordinary magnet, had a pole. Singular. Now, whilst no reputable scientist would argue that a magnetic monopole could open an inter-dimensional portal, its existence isn't outside the realms of possibility and if recent reports are anything to go by, it could depend on an otherwise mundane metallic element that you can find skulking around near the bottom of the Periodic Table - holmium.

Meera Senthilingam

And Hayley Birch will be revealing the truth about such mythical monopoles in next week's Chemistry in its Element. Until then, I'm Meera Senthilingam and thank you for listening.


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.



Produced by The Naked Scientists.


Periodic Table of Videos

Created by video journalist Brady Haran working with chemists at The University of Nottingham.