A Gist about Rhenium [Re] and its Discovery
Rhenium is a silvery-greyish chemical solid at the state of 20°C and has an atomic number of 75. This compound is present in the d-block, period 7, and 6th group in the Mendeleev’s Periodic Table. This is a transition metal in the 3rd of the table and is regarded asone of the rarest elements to be found in the earth’s crust. Rhenium is denoted as [Re].
One of the interesting facts about its discovery is that Rhenium is the 2nd and last compound to be noted for a stable isotope. Except for Francium, the rest of the elements present in nature are all said to possess high radioactivity. The credits for the discovery goes to a Japanese chemist named ‘Masataka Ogawa’, who found the compound in 1908 and isolated the same in 1919.
Also noting that Otto Berg, Walter Noddack, and Ida Noddack, are appreciated for Rhenium’s nomenclature in 1925. The element was named as “Rhenium” based on the major European River ‘Rhine’.
The Physical Properties of Rhenium
The symbol of Rhenium is Re.
Regarded to be quite heavy.
Ores of molybdenum and platinum are noted to have a minimal presence of Rhenium. But not available as a mineral characteristic.
Next to Tungsten, the element Rhenium has the highest Melting point.
Located at the d-block, 7th group, and 6th period in the Periodic Table.
Solid structure at the state of 20°C.
Possesses a low melting point.
Silvery-greyish solid metal.
Hexagonal close packing (HCP) crystal structure.
Good stability for high-temperature conditions.
Rhenium is created by making use of the oxidised smelter residues that are derived when chemically processing the compound ‘molybdenite’.
Extremely rare element to be found on earth.
Pointing the Chemical Properties of Rhenium
The electronic configuration is [Xe]4f14 5d5 6s2.
75 is the atomic number of Rhenium.
3185°C, 5765°F and 3458 K is the Melting point.
Atomic mass is 186.23 g.mol -1.
The Relative atomic mass is 186.207.
The Boiling point is 5590°C, 10094°F, and 5863 K.
187Re is the Rhenium’s Key Isotope known.
Third-row transition element.
20.8 g cm−3 is the density.
Details on the Isotopes of Rhenium [Re]
Only 1 stable isotope is noted for Rhenium which is rhenium-185. Again, this is the rarest isotope ever and is sometimes observed in the metallic elements Tellurium and Indium.
A total count of 33 isotopes are recognized for Rhenium, that ranges from 160Re to 194Re, all of them termed to be unstable and 183Re is the longest-present isotope among all with a half-life of 7- days.
187Re and 185Re are the 2 unstable, naturally-occurring isotopes of Rhenium, yet have the longest half-life of approximately 1010 years. The rhenium-186m is one of the key isotopes well-known for its longest metastable half-life of 200,000 years approximately. However, the state of ionic charges in the element majorly influences the half-life duration of these isotopes.
As a notable point, the beta decay value of 187Re is effective during ore dating of rhenium–osmium and is found to be lowest in its available energy among all the other radionuclides present. The value is 2.6 keV.
The Important Rhenium Uses across Sectors
The uses of Rhenium are majorly noted in the domains of petroleum and the making of superalloys. Besides these, even fields such as photography, hydrogenation reactions and a few more areas make use of Rhenium. Let us learn the applications of Rhenium for all the mentioned cases and more from the following.
Rhenium acts as a superalloy for the high-temperature gas turbine engines such as CMSX-4 (2nd gen) and CMSX-10 (3rd gen) respectively.
This element is notable for amplifying the strength of high-temperature, similar to other nickel-based superalloys present. This is possible as Rhenium improves the creep strength of the element added with it.
Tungsten-Rhenium wires are manufactured to develop a wiring system that is high on ductility even after the recrystallization processes. The same is used as ‘thermocouples’ for temperature measurements, up to the range of 2200 °C.
The undesirable phases of TCP (topologically close-packed) unstable microstructures are caused when Rhenium reacts with certain superalloys.
Rhenium plays a major role in the photoflash aspect of photography.
In the production of lamps and filaments, tungsten and molybdenum are added with Rhenium to form the needed alloy.
Rhenium-Platinum alloys are good catalytic reformers to achieve high-octane liquid products.
The use of Rhenium transition metal as a superalloy is also observed in the case of making high-temperature parts of a jet. Above the average level of jet parts production is possible due to Rhenium and its properties.
Apart from being an additive for molybdenum and tungsten, this compound is also preferred in hydrogenation fine chemicals.
Conclusion
Rhenium is a silvery-grey solid chemical structure, classified in the 7th group and 6th period of the d-block in the periodic table and noted to be a transition metal. This element was discovered by a Japanese chemist in 1908, and 1919 was the year of isolation. This element is both good concerning its high-temperature stability and low melting points. The rhenium-185 is the rarest, unstable and naturally-occurring key isotope of Rhenium. The Rhenium uses are observed in an array of domains including, lamp production, superalloys, hydrogenation chemical reactions, catalytic procedures, gas turbine making, and even in the production of jet parts.
FAQs on Rhenium
1. What is Rhenium and what are its key physical properties?
Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. Its key properties include:
- High Density: It is one of the densest elements, surpassed only by platinum, iridium, and osmium.
- High Melting Point: It has the third-highest melting point of any element (3186 °C), after tungsten and carbon.
- High Boiling Point: It has the highest boiling point of all elements (5596 °C).
2. Where is Rhenium located in the Periodic Table and what is its electronic configuration?
Rhenium is located in Group 7 and Period 6 of the Periodic Table, placing it in the d-block of elements. Its electronic configuration is [Xe] 4f¹⁴ 5d⁵ 6s². This configuration, with five unpaired d-electrons and two s-electrons, allows it to exhibit a wide range of oxidation states.
3. What are the most important uses of Rhenium?
The primary use of Rhenium is in creating high-performance superalloys. Key applications include:
- Jet Engines: Nickel-rhenium superalloys are used to manufacture high-pressure turbine blades and exhaust nozzles in jet engines, allowing them to operate at extremely high temperatures.
- Catalysts: Platinum-rhenium catalysts are essential in the petroleum industry for producing high-octane, lead-free gasoline through a process called catalytic reforming.
4. Why does Rhenium exhibit such a wide range of oxidation states?
Rhenium exhibits numerous oxidation states, from -3 to +7, because its valence electrons in the 5d and 6s orbitals are very close in energy. This allows a variable number of electrons to participate in chemical bonding. The most common and stable oxidation states are +7, +6, +4, and +2. The +7 state, found in compounds like rhenium heptoxide (Re₂O₇) and perrhenates (ReO₄⁻), is particularly significant.
5. Why is Rhenium considered a rare and expensive metal?
Rhenium's high cost is due to a combination of rarity and difficult extraction. It has a very low abundance in the Earth's crust, averaging about 1 part per billion. Furthermore, Rhenium does not occur in its own distinct mineral; it is primarily obtained as a by-product of processing molybdenum and copper ores. This complex and multi-stage extraction process, coupled with high demand in critical industries like aerospace, makes it one of the most expensive metals.
6. How is Rhenium extracted commercially?
Rhenium is not mined directly. It is commercially extracted from the flue gases and dusts generated during the roasting of molybdenite ores. The process involves separating it from the dust, converting it into a soluble salt like ammonium perrhenate (NH₄ReO₄), and then reducing this compound with hydrogen gas at high temperatures to produce pure rhenium metal powder.
7. What are perrhenates and why are they chemically important?
Perrhenates are chemical compounds containing the perrhenate ion (ReO₄⁻), where Rhenium is in its highest oxidation state of +7. They are the salts derived from perrhenic acid (HReO₄). Perrhenates, such as ammonium perrhenate, are chemically important because they are the most common commercial form of rhenium and serve as a crucial intermediate in the purification and extraction of the pure metal from ore by-products.
8. Is Rhenium considered harmful to humans?
Pure metallic Rhenium is generally considered to have low toxicity due to its chemical inertness. However, very little is known about the long-term effects of exposure. As a precaution, its dust and soluble compounds, such as rhenium halides and perrhenates, should be handled with care as they are considered potentially hazardous. Proper safety measures should always be used when working with Rhenium in any form.
