Periodic Table > Terbium
 

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 1356 oC, 2472.8 oF, 1629.15 K 
Period Boiling point 3230 oC, 5846 oF, 3503.15 K 
Block Density (kg m-3) 8267 
Atomic number 65  Relative atomic mass 158.925  
State at room temperature Solid  Key isotopes 159Tb 
Electron configuration [Xe] 4f96s2  CAS number 7440-27-9 
ChemSpider ID 22397 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 abstracted compact disk symbol used here reflects the use of the element in its manufacture
Appearance
A rare, silvery metal used in electronic devices.
Uses
Terbium is used to dope calcium fluoride, calcium tungstate and strontium molybdate, all used in solid-state devices. Terbium salts are used in laser devices, but otherwise this element is not widely used.
Biological role
Terbium has no known biological role, and has low toxicity.
Natural abundance
Terbium can be recovered from the mineral monazite by ion exchange and solvent extraction, and from euxenite, a complex oxide containing 1% or more of terbium. It is usually produced commercially by reducing the anhydrous fluoride or chloride with calcium metal.
 
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) 2.330 Covalent radius (Å) 1.81
Electron affinity (kJ mol-1) Unknown Electronegativity
(Pauling scale)
Unknown
Ionisation energies
(kJ mol-1)
 
1st
565.770
2nd
1111.510
3rd
2113.992
4th
3839.148
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 4, 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  159Tb 158.925 100
 

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)
28.91 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)
- - - 1.92
x 10-9
4.18
x 10-6
9.88
x 10-4
5.85
x 10-2
1.15 12.5 88 -
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History

Terbium was first isolated in 1843 by the Swedish chemist Carl Mosander at Stockholm. He had already investigated cerium oxide and separated a new element from it, lanthanum, and now he focussed his attention on yttrium, discovered in 1794, because he thought this too might harbour another element. In fact Mosander was able to obtain two other metal oxides from it: terbium oxide (yellow) and erbium oxide (rose pink) and these he announced in 1843. This was not the end of the story, however, because later that century these too yielded other rare earth elements (aka lanthanoids). Today these elements are easily separated by a process known as liquid-liquid extraction.

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Podcasts

Listen to Terbium Podcast
Transcript :

Chemistry in its element - Terbium


(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 a colourful element with a multitude of uses. Bringing you the luminous chemistry of terbium, here's Louise Natrajan. 

Louise Natrajan 

As a synthetic chemist whose job it is to study the chemistry of the lanthanide ions, I am often asked which one is my favourite. This is not however a particularly easy question to answer, and my reply often varies depending on which element I have been playing with in the lab that week. You see, although a common perception is that lanthanides all have the same chemistry, and some have even described them as 'boring', each element has its own unique and special characteristics. 

Terbium, element number 65, is no different and lies in the middle of the lanthanide series in between gadolinium and dysprosium. It is one of the rarer rare earth elements, although it is still twice as common as silver in the Earth's crust. It is also one of the four lanthanide elements that are named after the place of its discovery, Ytterby in Sweden, 'the village of the four elements'. Terbium was first isolated after several of the other lanthanides in Stockholm, Sweden by Carl Gustav Mosander in 1843, who suspected that the mineral Yttria discovered previously in 1794 by Johan Gadolin might harbour other elements, just as ceria had done previously. Mosander was Professor of Chemistry and Mineralogy at the Karolinska Institute in Stockholm, and he succeeded in showing that yttria was mainly yttrium oxide, but also contained two other oxides, terbium oxide, which is yellow in colour and erbium oxide, which is a rose pink colour. 

Compounds of terbium generally contain the terbium ion in its 3+ valence state, however in some solids, terbium is quite unusual in that it can exist in the 4+ valence state, due to the fact its fourth ionisation energy is relatively low so it attains a more stable half filled shell of electrons just as its neighbour gadolinium. The most striking property of terbium compounds comes from its spectroscopic and optical properties, which makes it one of the more exciting and studied lanthanide elements. 

Terbium in the +3 state radiates an aesthetically pleasing luminous green colour when the correct wavelength of energy is used to excite the atoms. This is because terbium 3+ ions are strongly luminescent, so strong in fact, that its luminescence can often be seen by the naked eye The human eye is particularly sensitive to the colour green and even small amounts in the right compound are easily detectable by eye. This bright colour renders terbium compounds particularly useful as colour phosphors in lighting applications, e.g. in fluorescent lamps, where it is a yellow colour, and as with europium(III) which is red, provides one of the primary colours in TV screens; who knew that Tb could be in your TV set! Some terbium compounds are also quite unusual in that they display a phenomenon known as triboluminescence. This is a process where light is emitted when a crystalline solid compound is fractured, so a fracture in the crystalline lattice for example will result in the emission of bright green light that can be seen. The triboluminescence of Tb containing compounds can be exploited in fibre optic sensors that measure changes in mechanical stress e.g. pressure, strains, vibrations and acoustic emissions and has been proposed to be of use in monitoring structural stress in aeroplane wings! 

Molecular terbium compounds have also found use in biological and medical research. The green emission of terbium compounds is very long lived, typically in the order of milliseconds, which means it can be detected long after the fluorescence of biological molecules has decayed away, and hence can be used as a biological probe to signal certain events. The luminescence from molecular Tb compounds can be switched on and off by chemical manipulations to the molecule and this has been exploited in the fabrication of sensors that measure the partial pressure of oxygen for example. Other Tb compounds have been used for the determination and quantification of drugs, in DNA and RNA assays, for the determination of protein structures and probes are currently being developed for in vitro cell imaging to aid in the early detection and treatment of diseases including cancer. Finally, Tb phosphors are also used as security inks and are found in anti counterfeit Euro bank notes, although europium is perhaps a little more famous for this role. 

Besides its fantastic green colour, terbium also finds a niche role in its use in an alloy called Terfenol-D. Terfenol-D is an alloy of Tb, Fe and Dy and is a material that changes shape in a magnetic field; so called magnetostriction. It is used commercially in a speaker called the 'SoundBug', which turns any flat surface into a speaker! The device works by vibrating any material onto which it is placed such as a table or desk, making it into a speaker. 

So what do TV screens, Euro bank notes, triboluminescence and SoundBug speakers all have in common? Terbium of course! So, now when someone asks me which lanthanide is my favourite, I'd have to say that terbium is definitely one of them and it is certainly far from being boring! 

Meera Senthilingam 

No, not boring at all if it helps make television, sound speakers and currency come into existence. That was Manchester University's Louise Natrajan explaining the many uses of terbium. Now next week a special treat, as we have an element that's so new that it hasn't even officially been named yet. 

Sigurd Hofmann 

In 1996 we set about producing element 112, inside a particle accelerator. We bombarded a lead target - that has 82 protons - with a zinc beam containing 30 protons for one week, and were able to detect a single atom of an element with 112 protons - element 112. 

Meera Senthilingam 

And Sigurd Hofmann, one of the discoverers of element 112 will be explaining the chemistry of this new element and also reveal what he and his team at the GSI Helmolt Centre for Heavy Ion Research in Germany are hoping to name it. So to find out, join us on next week's Chemistry in its Element. Until then I'm Meera Senthilingam from the nakedscientists.com and thank you for listening. 

(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.