Rhenium Definition, Facts, Symbol, Discovery, Properties, Uses

Table Of Contents

What is Rhenium
Where is it Found in Nature
History of Rhenium
Classification and Position of the Element on the Periodic Table [1]
Properties of Rhenium [1, 2, 3]
Atomic Data of Rhenium [1, 2, 3]
What is Rhenium Used for
Rhenium Toxicity
Interesting Facts
Rhenium Price

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.

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].

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].

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].

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

Group	7
Period	6
Block	d

Location of Rhenium in the Periodic Table

Properties of Rhenium ^{[1, 2, 3]}

General Properties
Relative Atomic Mass (Atomic Weight)	186.207
Molar Mass	186.207 g/mol
Physical Properties
Color	Silvery white
Luster	Metallic
Odor	Unknown
Malleability	Yes
Ductility	Yes
Melting Point/Freezing Point	3186 °C, 5765°F
Boiling Point	5596 °C, 10094°F
Density	21 g/cm3
State of Matter at Room Temperature	Solid
Hardness	7 Mohs
Yield Strength	43 ksi
Electrical Conductivity	5.8 × 10⁸Sm^-1
Work Function	0.7 eV
Thermal (Heat) conductivity	48 W m^-1 K^-1
Molar Heat Capacity	25.48 J/mol k
Chemical Properties
Flammability	Unknown
Oxidation state/Oxidation number	−3, −1, +1, +2, +3, +4, +5, +6, +7

Atomic Data of Rhenium ^{[1, 2, 3]}

Atomic Number	75
Valence Electrons	5d 6s
Quantum Numbers
– n	5
– ℓ	2
– m_ℓ	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	2.760 Å
Atomic Structure
– Number of Electrons	75
– Number of Neutrons	111
– Number of Protons	75
Radius of Atom
– Atomic Radius	2.16 Å
– Covalent Radius	1.41 Å
Electronegativity	1.9
Ionization Energy (kJmol^-1)	1st	2nd	3rd	4th	5th	6th	7th
	755.82

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 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].

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 Price

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

References

What is Rhenium

Where is it Found in Nature

History of Rhenium

Origin of its Name

Who Discovered Rhenium

When and Where was it Discovered

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

Properties of Rhenium [1, 2, 3]

General Properties

Physical Properties

Chemical Properties

Atomic Data of Rhenium [1, 2, 3]