Periodic Table > Neodymium
 

Terminology


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


For more information on Murray Robertson’s image see Uses/Interesting 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 1016 oC, 1860.8 oF, 1289.15 K 
Period Boiling point 3074 oC, 5565.2 oF, 3347.15 K 
Block Density (kg m-3) 7000 
Atomic number 60  Relative atomic mass 144.24  
State at room temperature Solid  Key isotopes 142Nd 
Electron configuration [Xe] 4f46s2  CAS number 7440-00-8 
ChemSpider ID 22376 ChemSpider is a free chemical structure database
 

Interesting Facts 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 / Interesting Facts

 
Image explanation
The imagery and symbols used here suggest the use of the element in the manufacture of purple glass.
Appearance
A fairly common but little used silvery metal. It is contained in some alloys for magnets, glass, glazes and lighter flints. Neodymium dust and salts are very irritating to the eyes.
Uses
Neodymium is present in misch metal up to 18%. This alloy is used in such products as cigarette lighters where a light flint operates. Neodymium is also a component, along with praseodymium, of didymia, a special glass used in goggles in glass blowing and welding. The element colours glass delicate shades of violet, wine-red and grey. It is used to make glass which transmits the tanning rays of the sun but not the harmful infrared rays.
Biological role
Neodymium has no known biological role, is moderately toxic and a known eye irritant.
Natural abundance
The principal sources of most lanthanides are the minerals monazite and bastnaesite. From these neodymium can extracted by ion exchange and solvent extraction techniques. The element can also be obtained by reducing the anhydrous chloride with calcium.
 
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) 2.390 Covalent radius (Å) 1.88
Electron affinity (kJ mol-1) Unknown Electronegativity
(Pauling scale)
1.140
Ionisation energies
(kJ mol-1)
 
1st
533.081
2nd
1034.322
3rd
2132.324
4th
3898.004
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/ 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 / Isotopes

 
Common oxidation states 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  142Nd 141.908 27.2
  143Nd 142.91 12.2
  144Nd 143.91 23.8 2.1 x 1015
  145Nd 144.913 8.3
  146Nd 145.913 17.2
  148Nd 147.917 5.7
  150Nd 149.921 5.6 1.33 x 1020 β-β- 
 

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 / Temperature - Advanced

 
Molar heat capacity
(J mol-1 K-1)
27.45 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)
- - 4.55
x 10-11
7.62
x 10-7
4.83
x 10-4
4.41
x 10-2
1.07 13.4 101 - -
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History

Neodymium was discovered in Vienna in 1885 by Karl Auer. Its story began with the discovery of cerium, from which Carl Gustav Mosander extracted didymium in 1839. This turned out to be a mixture of lanthanoid elements, and in 1879, samarium was extracted from didymium, followed a year later by gadolinium. In 1885, Auer obtained neodymium and praseodymium from didymium, their existence revealed by atomic spectroscopy. Didymium had been studied by Bohuslav Brauner at Prague in 1882 and was shown to vary according to the mineral from which it came. At the time he made his discovery, Auer was a research student of the great German chemist, Robert Bunsen who was the world expert on didymium, but he accepted Auer's discovery immediately, whereas other chemists were to remain sceptical for several years.


A sample of the pure metal was first produced in 1925.

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Podcasts

Listen to Neodymium Podcast
Transcript :

Chemistry in its element - neodymium


  (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, two for the price of one this week.   Here's Andrea Sella.

 

Andrea Sella

As a graduate student I used to seal off NMR samples under vacuum. As the glass was heated by the torch, the flame would blaze with the fierce orange glow of the sodium lurking in the pyrex. It was all the glassblowing I could do. Anything more serious required a trip down to the ground floor to see our wizard glassblower, Geoffrey Wilkinson, a lovable rogue from the Black Country with an infectious laugh, and wit was as sharp as a razor.

One day, as he stood at his lathe with an orange inferno raging before him I asked him about the glasses he was wearing. "Didymium" he answered cryptically, and then noticing my blank look, he added "Cuts out the light. Try them." He passed me his specs, the lenses of a curious greeny-grey colour. I slipped them on and suddenly the flame was gone. All I could see was a red-hot piece of spinning glass unobscured by the glare. I gawped in wonder until Geoff pulled the specs off my face saying "Give 'em back ya fool" and went back to his work. 

Didymium is not a name you will often find in textbooks these days. It is the name of a pair of elements which lie next to each other in the lanthanide or rare earth series - what used to be the Wild West of the periodic table. The fourteen elements that constitute the series are remarkable for their similarity. Nowhere else does one find a group of elements that so resemble each other in their chemical properties. Hence these elements proved incredibly difficult to separate from each other and purify. And to make matters worse, unlike other metals, the colours of   rare earth metal compounds were pale changed little from one compound to the next, making it even harder to work out whether your material was pure. Amongst the many claims for the discovery of new elements was a report in 1839 by the Swedish chemist Carl Gustav Mosander of a supposed element he called "Didymium" - after the Greek word for twin. 

The invention of spectroscopy by Gustov Kirchoff and Robert Bunsen (yup, he of the Bunsen burner) now came into its own. It was soon realized that the spectre of the rare earths were very characteristic, with sharp gas-phase-like lines both in the solid and solution. At last there was a means of establishing purity. 

 

Bunsen, who, by the 1870s, was the world's leading authority on the spectroscopy of the rare earths set this element as a problem for one of his students Carl Auer, who began to carry out the hundreds of fractional crystallizations necessary to get it pure. By 1885 it was clear that Auer had not one but two elements on his hands - a bluish lilac one he called "Neodymium", the new twin - and a green one he named "Praseodymium" - the green twin, each with their own spectra which summed together were the same as those of Mosander's material. Bunsen was delighted and immediately gave his approval to his student's work. 

 

But it would not be until the 1940s before fast and effective methods for the separation of the lanthanides would be developed.    Rather than the series of excruciatingly tedious crystallizations, the American chemists led by Frank Spedding described ion exchange methods and then within a few years solvent extraction became prevalent and produced kilogram quantities of these elements. Suddenly, commercial applications became a real prospect.

 

Because the ions themselves have unpaired electrons, their magnetic properties have proved fascinating to scientists and lucrative to entrepreneurs. An alloy of neodymium, iron and boron discovered in the 1980s is ferromagnetic, yielding permanent magnets over 1000 times stronger than anything ever seen before.    Neodymium ion borade magnets have not only found their way into almost billions of electric motors and electronic devices around the world but also into wonderful toys for children.

 

On the other hand, the sharp spectral lines that so fascinated Bunsen and generations of spectroscopists since, imply very precise electronic states. Embedding neodymium into synthetic gemstones such as garnet resulted in the Neodymium:YAG laser, the workhorse of industrial laser cutting tools with its brilliant infrared lines. Your personalised ipod was probably engraved with a YAG.   Coupled with a frequency doubling crystal a YAG gives us the bright green laser pointer than some lecturers like to show off with.

 

But some lateral thinking in the 1940s by chemists at Corning Glassworks in the US gave the invention that changed glassblowing forever. Someone spotted that both praseodymium and neodymium had absorption lines corresponding almost exactly with that annoyingly brilliant orange sodium line. Corning began producing "Didymium glass" which acts as an optical notch filter to cut out the glare and effect remains as astonishing to me today as it was the first time I saw it. When, a few years ago, one of our glassblowers here at UCL retired, he phoned me up on his last day. "I have something for you," he said mysteriously. I went down to the basement and shook his hand to wish him well. And then, to my delight, he handed me his specs. "Didymium," he said, "You'll need these."

 

Chris Smith

 

Andrea Sella with the story of Didymium, two elements rolled into one.   And Andrea is back next week with a taste of a metal that melts in your mouth and possibly also in your hands. 

 

Andrea Sella

 

But I'm sure you really want to know is, if this really is the M & M element, what does it taste like? I knew you would ask. So I had a quick lick a couple of days back and the answer is it doesn't actually taste of very much to be honest. There's a faintly astringent and metallic taste which lingers on your tongue for few hours.   And when it is molten, sorry I'll leave that experiment for someone more intrepid than I.

 

Chris Smith

 

And you can catch the story of Gallium, which is what he was eating, with Andrea Sella on next week's Chemistry in its Element, that's of course assuming that his element eating antics haven't poisoned him in the meantime.    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. 

 

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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.