Chemistry Learner

It's all about Chemistry

Rhenium

What is Rhenium

A rare earth metal, rhenium (pronounced as REE-nee-em) belongs to the family of transition metals denoted by the chemical symbol Re [1]. It has 33 isotopes with known half-lives, their mass numbers ranging from 160 to 192. Naturally occurring rhenium is a mixture of a stable isotope, Rhenium-185 and a radioactive isotope, Rhenium-187 [2, 9]. It shows moderate reactivity with various compounds, except water. Though its usual commercial form is powder, foils, sheets, pellets, bars, and rods are also produced to be used for different applications.

Rhenium

Where is it Found in Nature

Chile has the world’s largest Rhenium reserve followed by Peru, USA, and Kazakhstan [10].

Re, for commercial purposes, is extracted from molybdenum roaster-flue dust found in copper-sulfide ores. It does not exist in nature freely or in the form of compounds along with any mineral ore deposits [6].

Rhenium Color

History of Rhenium

Origin of its Name

The element derives its name from the Latin word for the river Rhine, Rhenus [3].

Who Discovered Rhenium

In 1925, Walter Noddack, Ida Tacke, and Otto Berg discovered the element in Berlin [2].

Rhenium Powder

When and Where was it Discovered

The Russian Chemist, Dmitri Mendeleev who created the periodic table in 1869, anticipated the existence of other elements that were not yet discovered after noticing gaps in the table. He predicted two elements having similar properties to manganese and named them eka-manganese and dvi-manganese, respectively.

In 1913, the existence of rhenium was once again predicted by the English physicist Henry Moseley who discovered a new method of arranging elements in the periodic table by their atomic number instead of atomic weight as done before. However, it resulted in gaps in the table due to the absence of elements still undiscovered, rhenium being one of them.

It was only in 1925 when Noddack, Tacke, and Berg discovered rhenium in platinum ores and columbite along with another element called technetium through X-ray analysis. Despite several disagreements and arguments, the existence of Re was finally confirmed and published in the periodic table [2].

Rhenium Metal

 Classification and Position of the Element on the Periodic Table [1]

Group 7
Period 6
Block d

Properties of Rhenium [1, 2, 3]

General Properties

Relative Atomic Mass (Atomic Weight) 186.207
Molar Mass (g/mol) 186.207

Physical Properties

Color Silvery white
Luster Metallic
Odor Unknown
Malleability Yes
Ductility Yes
Melting Point/Freezing Point (°C) 3186
Boiling Point (°C) 5596
Density (g/cm3) 21
State of Matter at Room Temperature Solid
Hardness (Mohs) 7
Yield Strength (ksi) 43
Electrical Conductivity (Sm-1) 5.8 × 108
Work Function (eV) 0.7
Thermal (Heat) conductivity (W m-1 K-1) 48
Molar Heat Capacity (J/mol k) 25.48

Chemical Properties

Flammability Unknown
Oxidation States 7 6 4 2 -1

Atomic Data of Rhenium [1, 2, 3]

Atomic Number 75
Valence Electrons 5d 6s
Quantum Numbers
–          n 5
–          ℓ 2
       –      m 2
       –      m s +1/2
Ground State Electron Configuration [Xe] 4f14 5d5 6s2
Primary XPS Region Re4f
Crystal Structure hcp: hexagonal close-packed
Lattice Constants (Å) 2.760
Atomic Structure
–          Number of Electrons 75
–          Number of Neutrons 111
–          Number of Protons 75
Radius of Atom
       –       Atomic Radius (Å) 2.16
       –       Covalent Radius (Å) 1.41
Electronegativity 1.9
Ionization Energy

(kJmol-1)

1st 2nd 3rd 4th 5th 6th 7th
755.82

Rhenium Bohr Model

What is Rhenium Used for

  • The element is added to tungsten and molybdenum-based alloys used in oven filaments and tubes of X-ray machines to increase ductility at higher temperatures [1, 5]. It is also combined with nickel alloys for making single-crystal superalloys used for manufacturing turbine blades [1, 7].
  • It is used in electrical contact materials for its good wear resistance and ability to withstand arc corrosion [1].
  • As rhenium is resistant to sulfur, nitrogen, and phosphorous poisoning, it is used as a catalyst in the hydrogenation of fine chemicals, disproportionation of alkenes, and also in the production of unleaded, high-octane gasoline when combined with platinum [2, 5].
  • It is used in electric flash lamps required in photography, filaments of mass spectrometers, and ion gauges [3].
  • Rhenium-tungsten wire is used in furnace parts and thermocouples for measuring temperature up to 2,200°C, [5]. It is also required for welding applications, electronics, and making wire mesh grids in aerospace equipment [11].
  • The element is ideal for use in rocket motors because of its high-temperature resistance ability.
  • Another occasional application is in the plating of jewelry [8].

Rhenium Alloys

Rhenium Toxicity

Accidental contact with skin or eye may cause severe burns and irritation. If inhaled or ingested, it may lead to irritation of the digestive and respiratory tract [8].

Rhenium Bar

Interesting Facts

  • Rhenium has the highest melting point after tungsten and carbon [4].
  • Rhenium-molybdenum alloys are believed to exhibit superconductive properties at 10 K [5].
  • Rhenium-188, a high energy beta-emitting radioisotope, obtained from tungsten-188/rhenium-188 (W-188/Re-188) generator might be effective in cancer therapy and nuclear medicine [12].

Rhenium Darts

Rhenium Price

The metal costs somewhere between $2500 and $2800 per kilogram ($1260 and $1300 per ounce).

Rhenium Pellets

 

References:

  1. http://www.rsc.org/periodic-table/element/75/rhenium
  2. https://www.chemicool.com/elements/rhenium.html
  3. https://education.jlab.org/itselemental/ele075.html
  4. https://byjus.com/chemistry/rhenium/
  5. http://pubs.acs.org/cen/80th/rhenium.html
  6. https://www.livescience.com/39042-facts-about-rhenium.html
  7. https://link.springer.com/article/10.1007/s12598-015-0597-z
  8. https://www.lenntech.com/periodic/elements/re.htm
  9. https://pubchem.ncbi.nlm.nih.gov/compound/rhenium#section=Top
  10. http://www.miningoilgasjobs.com.au/mining/rocks,-metals—gems/metals/rhenium.aspx
  11. http://rhenium.com/molybdenum-rhenium.html
  12. https://www.hindawi.com/journals/ijmi/2013/290750/

Leave a Reply

Your email address will not be published. Required fields are marked *

Trending Topics