Periodic Table > Rhenium
 

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 Melting point 3185 oC, 5765 oF, 3458.15 K 
Period Boiling point 5590 oC, 10094 oF, 5863.15 K 
Block Density (kg m-3) 21023 
Atomic number 75  Relative atomic mass 186.207  
State at room temperature Solid  Key isotopes 187Re 
Electron configuration [Xe] 4f145d56s2  CAS number 7440-15-5 
ChemSpider ID 22388 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
Symbol based on the coat of arms of the Rhine League which regulated trade in the Middle Ages in that area.
Appearance
A metal with a very high melting point, second only to tungsten. It is usually available as a grey powder and is among the rarest metals on Earth. Rhenium is used in filaments and for catalysts in the chemicals industry.
Uses
Rhenium is used as an additive to tungsten and molybdenum-based alloys to impart useful properties. It is widely used for filaments for mass spectrographs. It is also used as an electrical contact material as it has good wear resistance and withstands arc corrosion. Rhenium catalysts are exceptionally resistant to poisoning and are used for the hydrogenation of fine chemicals.
Biological role
Rhenium has no known biological role.
Natural abundance
Rhenium does not occur uncombined in nature or as a compound in a mineral species. It is, however, widely spread throughout the Earth’s crust to the extent of about 0.001 parts per million. Commercial production of rhenium is by extraction from the flue dusts of molybdenum smelters.
 
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) 2.160 Covalent radius (Å) 1.41
Electron affinity (kJ mol-1) 14.468 Electronegativity
(Pauling scale)
1.900
Ionisation energies
(kJ mol-1)
 
1st
755.819
2nd
-
3rd
-
4th
-
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 6.5
Country with largest reserve base USA
Crustal abundance (ppm) 0.000188
Leading producer Chile
Reserve base distribution (%) 45.00
Production concentration (%) 54.10
Total governance factor(production) 6
Top 3 countries (mined)
  • 1) USA
  • 2) Chile
  • 3) Canada
Top 3 countries (production)
  • 1) Chile
  • 2) USA
  • 3) Peru
 

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 7, 6, 4, 2, -1
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  185Re 184.953 37.4
  187Re 186.956 62.6 4.16 x 1010 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)
25.48 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)
- - - - - - - 1.37
x 10-10
2.22
x 10-8
1.41
x 10-6
4.45
x 10-5
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History

The periodic table had two vacant slots below manganese and finding these missing elements, technetium and rhenium, proved difficult. Rhenium was the lower one and indeed it was the last stable, non-radioactive, naturally-occurring element to be discovered. In 1905, Masataka Ogawa found it in the mineral thorianite from Sri Lanka. He realised from lines in its atomic spectrum that it contained an unknown element. He wrongly thought it was the one directly below manganese and so his claim was discounted at the time. However, a re-examination of Ogawa’s original photographic spectra proved he had discovered rhenium.


The isolation of rhenium was finally achieved in May 1925 by Walter Noddack and Ida Tacke working in Berlin. They concentrated it from the ore gadolinite in which it was an impurity.

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Podcasts

Listen to Rhenium Podcast
Transcript :

Chemistry in its element - Rhenium


(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 one of the rarest elements on earth that seems to enjoy changing the laws of nature. Unraveling the mysteries of Rhenium, here's UCLA's Eric Scerri. 

Eric Scerri 

Rhenium is element 75 in the periodic table and in many ways a rather unusual element. It is one of the rarest elements on the Earth with an abundance of something like 1 part per million. It is also one of the densest elements, following only platinum, iridium and osmium and it is one of the highest melting point elements exceeded only by tungsten and carbon. 

Rhenium sits two places below manganese in the periodic table and its existence was first predicted by Mendeleev when he first proposed his periodic table in 1869. In fact this group is unusual in that, when the periodic table was first published, it possessed only one known element, manganese, with at least two gaps below it. The first gap was eventually filled by element 43 technetium, the second gap was filled by rhenium. But rhenium was the first to be discovered. 

It was first isolated in 1925 by Walter and Ida Noddack and Otto Berg in Germany. In the course of an extraction of epic proportions, they processed about 660 kg of the ore molybdenite in order to get just one gram of rhenium. These days rhenium is extracted more efficiently as the bi-product of the processes for the purification of molybdenum and copper, since rhenium often occurs as an impurity in the ores of these elements. 

The discoverers called their element, rhenium, after the Latin name Rhenus for the river Rhine close to the place where they were working. In fact the Noddacks and Berg believed that they had also isolated the other element missing from group 7, or element 43, that eventually became known as technetium, but it was not to be. 

As recently as the early years of the 21st century some researchers from Belgium and the US re-analyzed the X-ray evidence from the Noddacks and argued that they had in fact isolated element 43. But these claims have been hotly debated by many radiochemists and physicists and now have been finally laid to rest. 

But by an odd twist of fate, a Japanese chemist, Masataka Ogawa believed that he had isolated element 43 and called it nipponium back in 1908. His claim too was largely discredited but as recently as 2004 it has emerged that he had in fact isolated rhenium well before the Noddacks. 

Until quite recently no mineral containing rhenium combined with just a non-metal had ever been found. Not until 1992 that is, when a team of Russian scientists discovered rhenium disulphide at the mouth of a volcano on an islands off the east coast of Russia between the Kamchatka peninsula and the Japanese islands. 

The chemistry of rhenium is also rather interesting. For example, it shows the largest range of oxidation states of absolutely any known element, namely -1, 0, +1, +2 and so on all the way to +7, the last of which is actually its most common oxidation state. 

Now here is another oddity. Until the early 1960s it was believed that three bonds between any two atoms was as high as nature could go, as in the case of the nitrogen-nitrogen triple bond for example. But in 1964 Albert Cotton and co-workers in the USA discovered the existence of a metal-metal quadruple bond. Yes you guessed it, it was rhenium, or rather a rhenium compound namely the rhenium ion, [Re2Cl8]2+ [correction: this should be the two minus ion, not the two plus ion]

More recently an especially simple compound of rhenium, rhenium dibromide, has attracted a great deal of scientific attention because it is one of the hardest of all known substances. And unlike other super-hard materials, like diamond, it does not have to be manufactured under high pressure conditions. 

But what else is rhenium good for? What are some other applications? Well there are many of them. A good deal of the rhenium extracted is made into super-alloys to be used for parts in jet engines. Not surprisingly for a transition metal, rhenium is also a good catalyst. In fact a combination of rhenium and platinum make up the catalyst of choice in the very important process of making lead-free and high-octane petrol. Rhenium catalysts are especially resistant to chemical attack from nitrogen, phosphorus, and sulfur, which also makes them useful in hydrogenation reactions in various industrial processes. 

And just to go back to the Noddacks, and in particular Ida Noddack, it was she who first proposed in 1934 that nuclear fission might be possible as the result of the break up of a nucleus into fragments but her speculation was ignored and it had to wait until 1939 when Hahn, Strassmann and Meitner really discovered fission. Why was Noddack ignored? The most popular view seems to be that it was because her reputation had been damaged by her falsely announcing the discovery of element 43 in addition to the correct discovery of rhenium. 

Meera Senthilingam 

So its one of the hardest of all known substances, has a variety of oxidation states, and has the ability to make quadruple bonds, certainly a rule breaker. That was Eric Scerri from the University of California Los Angeles, revealing the secret powers of rhenium. Next week, a colourful luminous element. 

Louise Natrajan 

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 Turbium could be in your TV set! 

Meera Senthilingam 

And Manchester University's Louise Natrajan will be filling us in on the colourful story of terbium 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 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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Resources

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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.