Rhodium

12.4
102.906
[Kr] 4d85s1
103Rh
9
5
d
45
2, 8, 18, 16, 1
719.675
Rh
12.4
1963°C, 3565°F, 2236 K
3695°C, 6683°F, 3968 K
William Hyde Wollaston
1803
7440-16-6
22389
More Information
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Uses and Properties

Image Explanation

From vintage heirlooms to contemporary masterpieces, rhodium's lustrous touch enhances the allure of jewelry, making each piece a radiant testament to the enduring artistry of both the craftsman and the precious metal itself.

Appearance

A hard, shiny, silvery metal.

Uses

Rhodium's Radiance: Unveiling the Diverse Applications of a Precious Metal


In the realm of precious metals, one shining star stands out for its exceptional brilliance and versatility—Rhodium. As a member of the platinum group, Rhodium has transcended its role as a mere adornment in the world of jewelry to become a crucial component in various industries, contributing to technological advancements, environmental solutions, and even medical breakthroughs.

 

1. The Gleam of Luxury: Rhodium in Jewelry Design


Rhodium's most renowned application is in the world of jewelry, where its radiant luster and durability have earned it a coveted place. Often used as a plating material for white gold and silver, Rhodium bestows a dazzling, reflective finish to jewelry pieces. Its protective properties ensure that the jewelry not only maintains its original brilliance over time but also gains resistance against tarnish and scratches.

 

2. White Gold Alchemy: Rhodium's Contribution to Jewelry Aesthetics


In the creation of white gold jewelry, Rhodium plays a transformative role. While gold itself carries a warm, yellowish hue, white gold is achieved through alloying gold with other metals. To achieve the desired bright and reflective appearance associated with white gold, jewelry makers frequently turn to Rhodium plating. This not only enhances the metal's visual appeal but also provides an economical alternative to platinum.

 

3. Industrial Brilliance: Rhodium in Catalysis and Electronics


Beyond the glamour of jewelry, Rhodium finds itself at the core of crucial industrial processes. Rhodium's catalytic properties have positioned it as a catalyst in various chemical reactions, contributing to the production of essential compounds. In the electronics industry, Rhodium is utilized in the manufacturing of advanced microelectronics, such as semiconductors and resistors, owing to its exceptional conductivity and resilience.

 

4. Automotive Emission Control: Rhodium in Catalytic Converters


Rhodium's impact extends to the automotive industry, where it plays a pivotal role in catalytic converters. These devices, essential for reducing harmful emissions from vehicles, contain Rhodium as a catalyst. Rhodium assists in converting nitrogen oxides into less harmful substances, contributing significantly to environmental efforts to improve air quality and reduce pollution.

 

5. A Spark of Green Innovation: Rhodium in Hydrogen Fuel Cells


As the world turns toward sustainable energy solutions, Rhodium emerges as a key player in the development of hydrogen fuel cells. Rhodium-based catalysts facilitate electrochemical processes within these cells, promoting efficient conversion of hydrogen into electricity. This application aligns with the global shift towards clean energy, highlighting Rhodium's role in the pursuit of eco-friendly technologies.

 

6. Medical Marvel: Rhodium in Cancer Treatment Research


In the field of medicine, Rhodium has become a subject of research for its potential applications in cancer treatment. Rhodium-based compounds are being explored for their ability to selectively target and inhibit cancer cells. While still in the experimental stages, these studies hint at a promising future where Rhodium may contribute to innovative therapeutic strategies in the fight against cancer.

 

7. Timeless Restoration: Rhodium in Antique Object Preservation


The ability of Rhodium to resist tarnish and corrosion has found a unique application in the restoration of antique objects. Whether it's antique jewelry or historical artifacts, Rhodium plating provides a protective layer, revitalizing these treasures and preserving them for future generations.

 

8. Versatility in Electroplating: Rhodium's Industrial Applications


Rhodium's versatility in electroplating processes extends to a variety of industries. Beyond jewelry, Rhodium is used to electroplate a range of items, from fine writing instruments to industrial components. Its brilliant and corrosion-resistant finish makes it an ideal choice for enhancing the aesthetic appeal and durability of diverse products.

 

Conclusion: Rhodium's Dazzling Legacy Across Industries


From the sparkle of luxurious jewelry to the precision of advanced electronics and the promise of environmentally friendly technologies, Rhodium has woven its brilliance into the fabric of various industries. Its enduring luster and remarkable properties make it not just a symbol of opulence but a key player in shaping technological advancements and contributing to solutions for a more sustainable and healthier future. As Rhodium continues to illuminate new frontiers, its legacy remains one of radiance, resilience, and remarkable versatility across the diverse tapestry of human innovation.

History

In the vast expanse of the periodic table, Rhodium (R) stands as a luminary, its fascinating history intricately woven into the tapestry of scientific discovery and industrial innovation. From its humble origins to its current prominence in diverse fields, the journey of Rhodium is a testament to human curiosity, resilience, and the transformative power of a precious metal.

 

1. The Discovery of Rhodium: A Russian Revelation


The story of Rhodium began in the early 19th century when the exploration of platinum-group metals was in full swing. In 1803, English chemist William Hyde Wollaston isolated Palladium from platinum ore and observed residues with properties that hinted at the existence of an undiscovered element. However, it wasn't until 1804 that Russian chemist and inventor William Jacob Hjelm successfully isolated Rhodium from a sample of platinum ore sourced from the Ural Mountains.

Hjelm's groundbreaking discovery marked the birth of Rhodium, named after the Greek word "rhodon," meaning rose-colored, owing to the rosy hues observed in some of its compounds.

 

2. Early Struggles and Limited Recognition


Despite its initial discovery, Rhodium faced a period of relative obscurity. The challenges lay not only in its rarity but also in the difficulty of isolating it in pure form. Early attempts to extract Rhodium were hindered by the presence of other platinum-group metals, adding layers of complexity to the isolation process. It was only in the mid-1800s that advancements in chemical techniques enabled scientists to obtain Rhodium in a more refined state.

 

3. The Platinum Alchemist: Wilhelm Hittorf's Rhodium Isolation


The late 19th century saw renewed interest in Rhodium, with German chemist Wilhelm Hittorf making significant contributions to its isolation. Hittorf improved upon existing methods, refining the process of obtaining pure Rhodium. His work laid the foundation for future investigations into the metal's properties and applications.

 

4. Industrial Applications Take Root: Rhodium in Alloys


As the 20th century unfolded, Rhodium began to find its place in industrial applications, particularly in the realm of metallurgy. Its remarkable resistance to corrosion and ability to improve the hardness of alloys made it a sought-after component in the production of high-quality materials. Rhodium's role in strengthening platinum became particularly significant, contributing to advancements in materials science and manufacturing.

 

5. Radiance in the Jewelry Realm: Rhodium's Aesthetic Appeal


Rhodium's journey from industrial applications to the world of aesthetics began with its remarkable ability to impart a dazzling finish. Jewelry designers recognized the metal's potential to enhance the brilliance of precious metals, leading to the widespread use of Rhodium plating. This application not only bestowed a reflective luster upon jewelry but also provided a protective layer, preventing tarnish and scratches.

 

6. Automotive Catalyst: Rhodium's Environmental Impact


In the latter half of the 20th century, Rhodium assumed a pivotal role in the automotive industry. The metal's catalytic properties found application in catalytic converters, devices crucial for reducing harmful emissions from vehicles. Rhodium, alongside other platinum-group metals, catalyzes the conversion of pollutants, such as nitrogen oxides, into less harmful substances, contributing significantly to environmental efforts.

 

7. Technological Triumphs: Rhodium in Electronics


Advancements in electronics in the latter part of the 20th century brought Rhodium into the forefront of technological innovation. The metal's exceptional conductivity and resilience made it a key player in the production of advanced microelectronics, including semiconductors and resistors. Rhodium's contribution to the field underscored its versatility and adaptability to the evolving landscape of technology.

 

8. The Green Promise: Rhodium in Sustainable Energy


As the world grapples with the need for sustainable energy solutions, Rhodium emerges as a player in the development of hydrogen fuel cells. Rhodium-based catalysts play a crucial role in facilitating electrochemical processes within these cells, contributing to the efficient conversion of hydrogen into electricity. This application aligns with global initiatives to harness clean energy sources.

 

Conclusion: Rhodium's Enduring Brilliance and Future Promise


From its discovery in the Ural Mountains to its pivotal role in jewelry, industry, and cutting-edge technologies, Rhodium's history is one of continuous evolution and adaptation. Its enduring brilliance, catalytic prowess, and aesthetic contributions make Rhodium not just a rare element but a transformative force in the realms of science, industry, and art. As the world looks toward a future of innovation and sustainability, Rhodium's journey promises to unfold new chapters, leaving an indelible mark on the ongoing story of human progress and discovery.

Atomic Data

Atomic Radiues, Non-bonded (A): 2.10
Electron Affinity (kJ mol-1): 109.704
Covalent Radiues (A): 1.34
Electronegativity (Pauling Scale): 2.28
Ionisation Energies (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
719.675 1744.45 2996.83 - - - - -

Oxidation States and Isotopes

Common oxidation states 5, 4, 3, 2, 1, 0
Isotope Atomic Mass Natural Abundance Half Life Mode of Decay
103Rh 102.905 100 - -

Supply Risk

Relative Supply Risk: 7.6
Crustal Abundance (ppm): 0.000037
Recycle Rate (%): >30
Production Conc.(%) : 60
Top 3 Producers:
1) South Africa
2) Russia
3) Zimbabwe
Top 3 Reserve Holders:
1) South Africa
2) Russia
3) USA
Substitutability: High
Political Stability of Top Producer: 44.3
Political Stability of Top Reserve Holder: 44.3

Pressure and Temperature Data

Specific Heat Capacity: 243
Shear Modulus: Unknown
Young Modulus: Unknown
Bulk Modulus: Unknown
Pressure 400k Pressure 600k Pressure 800k Pressure 1000k Pressure 1200k Pressure 1400k Pressure 1600k Pressure 1800k Pressure 2000k Pressure 2200k Pressure 2400k
- - - - - 1.69 x 10-8 5.99 x 10-6 0.000571 0.0217 0.422 Unknown

Podcast

Transcript :



Rhodium is a lustrous metal that may be found among the elements that make up the group of Platinum. It occupies the 45th spot on the periodic table. The name Rhodium was originated from the Greek words "Rhodon," which may be translated as "rose." Because of its color, Rhodium salts are often colored red. This is why Rhodium is also called the "Rose Metal". In 2006, it was estimated that Rhodium cost six times as much as gold. Until now, Rhodium catalysts are used in a number of industrial processes, notably in catalytic carbonylation of methanol to produce acetic acid by the Monsanto process. It is also used to catalyze addition of hydrosilanes to molecular double bonds, a process important in manufacture of certain silicone rubbers. However, in recent years, Iridium is taking over such role. The highest oxidation state of Rhodium: +7, has been discovered by scientists: Sebastian Riedel from Berlin university and Mayara da Silva Santos from Freiburg university. Due to a great deal of factors, this has been of utmost significance. For instance, it may open the way for the characterization of other highly-oxidized Rhodium compounds. This makes Rhodium the third 4d transition element to form a formal +7 oxidation state, after technetium and ruthenium.

Rhodium is a metal that has a rich history. The history of this element dates back to the early 1800s. It was the English scientist William Hyde Wollaston who made the discovery of this element. In 1803, he stumbled across Rhodium. He obtained rhodium from a sample of platinum ore that was obtained from South America. After removing the Platinum and Palladium from the sample, he was left with a dark red powder. The powder turned out to be sodium rhodium chloride. Wollaston obtained Rhodium from the powder by treating it with hydrogen gas.

Rhodium is an extremely uncommon element that may be discovered on Earth. It produced in many different countries, although it is an extremely rare element. The main exporter of Rhodium is South Africa. This country accounts for about 80% of the global supply. A considerable number of workers are employed by the mining industry. Despite this, the market for rhodium is not very large. In fact, in the year 2019, less than 1.15 million ounces of Rhodium were consumed.

In recent years, the Rhodium price increased to a staggering $6,000 per ounce.

In North America, Rhodium is found with nickel and Copper in the Sudbury, Ontario area. When Nickel and Copper are processed, Rhodium is one among the by-products. it can be obtained by electrolysis. This element is also produced through fission. During the fission process, the element Uranium-235 is released as a radioactive by-product. In the resulting fuel rods, Rhodium can be found. It can be produced by electroplating on Platinum.

Rhodium is a silvery-white hard transition metal and it is known for its whiteness, and is a valuable precious metal. In most cases, additional elements are alloying elements with it in order to boost its resistance to abrasion. Rhodium-containing thermocouples have excellent stability in a wide range of temperatures. Due to its properties, it is one among the most important members of the platinum group.

Rhodium is hard, chemically inert and highly resistant to corrosion. It has a low density and resistance to acid attack. However, it is difficult to dissolve Rhodium in water or dilute nitric acid. Rather, Rhodium is dissolved in concentrated hydrochloric acid with sodium perchlorate.

Its boiling point is 3697ºC. This is more than the melting point of platinum, but is lower than the melting point of gold. Alternatively, it can be dissolved in hydrochloric acid. When plated, Rhodium is extremely hard and resistant to tarnish. It is also a good electrical contact material. Rhodium is known for its high reflectivity and low electrical resistance.

It is an important material for the jewelry industry. In particular, it serves a crucial function as a catalytic in a vast array of synthetic reactions. When combined with platinum, it is used as a coating for optical fibers and as an electrical contact material. Besides being a highly reflective substance, Rhodium is also useful in the manufacture of thermocouples by using its alloy material with Platinum. It is now used as a catalyst for catalytic converters. Catalytic converters help convert harmful exhaust gases into less toxic gases. They are important in reducing nitrogen oxides, which are also known as NOX emissions. Other uses include glass, fiber production, and bushings. It is used in making alloys with other metals. Rhodium alloys are found in aircraft turbine engines, laboratory crucibles, spark plugs, furnace windings and electrical contact materials. These alloys are used in jewelry and scientific instruments as well. Rhodium-platinum alloy, which is known for its resistance to oxidation, is used for x-ray filters for breast cancer diagnosis, and electrical contacts.

Another use of Rhodium is to produce drugs for respiratory disorders, depression, and asthma. Coating agents are a common use for rhodium in a variety of different manufacturing applications. Its luster makes it a desirable coating for sterling Silver, it is used in automobiles and other industrial processes.

References


  • W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.

  • Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.

  • J. S. Coursey, D. J. Schwab, J. J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions (version 4.1), 2015, National Institute of Standards and Technology, Gaithersburg, MD, accessed November 2016.

  • T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.

  • John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.

  • Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.