Periodic Table > Scandium
 

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 Melting point 1541°C, 2806°F, 1814 K 
Period Boiling point 2836°C, 5137°F, 3109 K 
Block Density (g cm−3) 2.99 
Atomic number 21  Relative atomic mass 44.956  
State at 20°C Solid  Key isotopes 45Sc 
Electron configuration [Ar] 3d14s2  CAS number 7440-20-2 
ChemSpider ID 22392 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 element’s name is derived from the Latin name for Scandinavia. The image reflects this with an ancient Scandinavian figurine and carved runic standing stone.
Appearance
A silvery metal that tarnishes in air, burns easily and reacts with water.
Uses
Scandium is mainly used for research purposes. It has, however, great potential because it has almost as low a density as aluminium and a much higher melting point. An aluminium-scandium alloy has been used in Russian MIG fighter planes, high-end bicycle frames and baseball bats.

Scandium iodide is added to mercury vapour lamps to produce a highly efficient light source resembling sunlight. These lamps help television cameras to reproduce colour well when filming indoors or at night-time.

The radioactive isotope scandium-46 is used as a tracer in oil refining to monitor the movement of various fractions. It can also be used in underground pipes to detect leaks.
Biological role
Scandium has no known biological role. It is a suspected carcinogen.
Natural abundance
Scandium is very widely distributed, and occurs in minute quantities in over 800 mineral species. It is the main component of the very rare and collectable mineral thortveitite, found in Scandinavia.

Scandium can be recovered from thortveitite or extracted as a by-product from uranium mill tailings (sandy waste material). Metallic scandium can be prepared by reducing the fluoride with calcium metal. It can also be prepared by electrolysing molten potassium, lithium and scandium chlorides, using electrodes of tungsten wire and molten zinc.
 
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) 2.15 Covalent radius (Å) 1.59
Electron affinity (kJ mol−1) 18.139 Electronegativity
(Pauling scale)
1.36
Ionisation energies
(kJ mol−1)
 
1st
633.088
2nd
1234.99
3rd
2388.655
4th
7090.65
5th
8842.88
6th
10679
7th
13315
8th
15254.3
 

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 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  45Sc 44.956 100
 

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)
568 Young's modulus (GPa) 74.4
Shear modulus (GPa) 29.1 Bulk modulus (GPa) 56.6
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - - 6.31
x 10-8
0.000129 0.03 1.8 43.6 91.3 - -
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History

In 1869, Mendeleev noticed that there was a gap in atomic weights between calcium (40) and titanium (48) and predicted there was an undiscovered element of intermediate atomic weight. He forecast that its oxide would be X2O3. It was discovered as scandium in 1879, by Lars Frederik Nilson of the University of Uppsala, Sweden. He extracted it from euxenite, a complex mineral containing eight metal oxides. He had already extracted erbium oxide from euxenite, and from this oxide he obtained ytterbium oxide and then another oxide of a lighter element whose atomic spectrum showed it to be an unknown metal. This was the metal that Mendeleev had predicted and its oxide was Sc2O3.

Scandium metal itself was only produced in 1937 by the electrolysis of molten scandium chloride.
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Podcasts

Listen to Scandium Podcast
Transcript :

Chemistry in its element: scandium


(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)

Meera Senthilingam

This week, an element whose existence had been expected, Here's David Linsay.

David Lindsay

Scandium, atomic number 21. It is the first of the transition metals, and its discovery is entwined with that of vertical neighbours yttrium and lanthanum. The Swedish island of Resarö, near Stockholm, became a hotbed of elemental discovery in the late eighteenth, and early nineteenth, centuries. A quarry near the village of Ytterby yielded two different mineral ores, from which the seventeen so-called "rare earth" elements were eventually identified, those being scandium, yttrium and the fifteen lanthanide elements.

In 1788, a Lieutenant Arrhenius found an unusual black rock near the town of Ytterby. He passed this on to the famous Finnish scientist Johan Gadolin, and the story of the discovery of the rare earths began.

In 1879, Lars Nilson, isolated the oxide of a new metal element from the minerals gadolinite and euxenite. Nilson was a student of the legendary Jacob Berzelius, himself discoverer of many elements. Nilson named this oxide scandia, after Scandinavia. The discovery of this element was especially notable, as, seven years previously, Mendeleev had used his periodic table to predict the existence of ten as yet unknown elements, and for four of these, he predicted in great detail the properties they should have. One of these four, Mendeleev predicted, should have properties very similar to boron, and he named this element "ekaboron", meaning "like boron". The metal of this new oxide, scandia, was indeed found to have similar properties to this "ekaboron", thus demonstrating the power of Mendeleev's construction. For example, Mendeleev predicted the element's molecular weight would be 44 and that it would form one oxide with formula Eb2O3; scandium has molecular weight 45, and forms scandium oxide, Sc2O3. Some of Mendeleev's predictions were even more detailed. He predicted that the carbonate of ekaboron would not be soluble in water, which scandium carbonate is not. He even made a prediction related to the discovery of the element - that it would not be discovered spectroscopically. Indeed, scandium produces no spectroscopic lines, so could not be identified by this method of analysis. However, it was another Swedish chemist, Per Theodor Cleve, who was also working on the rare earths, who noticed the similarity between Nilson's new element, and the ekaboron predicted by Mendeleev. Despite the discovery of the oxide of this new element, it would take almost another sixty years until pure, elemental scandium was prepared, being made by electrolysis of scandium chloride in the presence of lithium and potassium, at high temperature.

Scandium is the first of the transition metals. Many of the transition metals exhibit a very rich and varied chemistry, due to the fact that they can exist in a wide variety of oxidation states. Scandium, however, is limited to the plus three oxidation state, meaning its chemistry is not quite as diverse as some of its transition metal counterparts.

Scandium is very much a late starter compared to many of the other elements, due to its relatively low occurrence and the difficulty in obtaining it from its ores. For example, it wasn't until the 1960s when the first pound, or 450 grams, of high purity scandium was obtained. Compounds of scandium find use in organic chemistry. Like many of the lanthanides, the trifluoromethansulfonate, or triflate, of scandium finds use as a so-called Lewis acid, accepting a pair of electrons from a suitable organic molecule, and activating the organic molecule to take part in highly efficient and selective chemical reactions. Scandium is also the source of artificial natural light. This might sound like a contradiction, but when scandium iodide is added in very small amounts to mercury vapour lamps, it produces light that is very similar to natural sunlight, and these lamps are used for applications ranging from floodlights to film projectors.

Scandium is added in small amounts to aluminium, to produce an alloy which is very light, yet very strong. As such, it has found use as a material for high performance road and mountain bikes. The advent of new frame materials, such as carbon fibre and titanium, has somewhat lessened the popularity of scandium alloy bike frames, but many such frames are still being made today.

So, that's Scandium - the element first found in the late eighteenth century, and not isolated pure and in large quantities until the middle of the twentieth century. One which helped demonstrate the power of the periodic table, and which you'll find illuminating football fields, and in the frames of mountain bikes.

Meera Senthilingam

And bringing us into the light there, was Reading University's David Lindsay, with the bright, strong chemistry of scandium. Now next week an element providing one more punch in the fight to protect our environment.

Simon Cotton

As everyone knows chlorofluorocarbons, CFCs for short, have been widely used in the past for fridges and freezers as the refridgerant gas. CFCs contribute to both depleting the ozone layer and they are also greenhouse gases. Due to this their use in the developed world has largely ceased, meaning a good, environmentally friendly replacement is needed. Gadolinium may prove useful to the fridges of the future due to a process known as magnetic refridgeration or adiabatic demagnetisation.

Meera Senthilingam

And join Uppingham School's Simon Cotton, to find out how magnetic refridgeration using the ions of gadolinium will be keeping our food cool in the future, in next week's chemistry in its element. Until then, I'm Meera Senthilingam and thank you 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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Resources

Description :
A collection of visually stimulating and informative infographics about the elements, which would make a valuable addition to any science classroom.
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Description :
The periodic table allows chemists to see similarities and trends in the properties of chemical elements. This experiment illustrates some properties of the common transition elements and their compou...
Description :
In this experiment you will be looking at a group of transition elements chromium, molybdenum and tungsten.
 

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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.