Rhodium Facts: All About The Most Precious Metal On The Earth

Rhodium metal is a precious and transition metal that is silvery and very hard.

Today, rhodium is considered to be the most valuable, and one of the rarest elements found deep within the Earth's crust that a person can find. Due to these qualities, it is deemed to be a noble metal, just like gold, silver, and platinum.

Rhodium is a beautiful whitish-silver metallic element that is highly reflective and corrosion-resistant. It comes from the Greek word 'rhodon,' meaning 'rose.' Its chemical symbol is Rh, and its atomic number is 45.

A chemist from England, named William Hyde Wollaston, first discovered the metal in the year 1803. The metal is described as being malleable and shiny and was discovered just after palladium. This precious metal is obtained from the process of platinum mining refining.

At first, Wollaston was warned of the possibility of the new element in the platinum ore. Then, he was alerted by Hippolyte-Victor Collet-Descotils, a French Chemist. Consequently, he believed the red color appearing in platinum salts to be due to an unidentified metal present there.

After many chemical reactions, the platinum and palladium were removed from the platinum ore. After that, he was left with a dark red powder from the platinum salts, which was sodium rhodium chloride.

Classification Of Rhodium As A Chemical Element

Rhodium is among the non-radioactive metals, it is a part of the group that includes the six platinum group metals: platinum, rhodium, palladium, iridium, ruthenium, and osmium.

If it is brought in contact with oxygen, it will not react with oxygen easily. The rhodium is thus corrosion and oxidation resistant. It also acts as a great catalyst.

Oxides and Halides are the most common rhodium types you can find, and rhodium iodide is used to synthesize acetic acid. In contrast, the organic sodium rhodium chloride in dark red powder forms carbon and hydrogen bonds.

Rhodium comes from platinum ore, and platinum is a very rare metal. Hence, rhodium is even rarer. Therefore, the price of this rare element may rise or fall depending on the product that is used every day. As demand rises or falls, the supply and price change accordingly, too.

Rhodium makes up only about 0.000000007% of the Earth's crust, only forming up to one part per 200 million of the Earth’s crust. This means that the supply is already short, making the starting price significant.

The price is further influenced by demand, but not drastically. The supply here is the main factor in making this metal the most expensive in the world.

Chemical Properties Of Rhodium

The chemical property of rhodium has one valence electron in the 5s orbital. Possible oxidation states are 0, +1, +2, +3 (which is also known for being the most common), +4, +5, and +6. Rhodium compound is the form of rhodium that has halogens and oxygen.

It has a high electronegativity, and it even holds electrons tightly when it is part of a compound. It is a solid that is not soluble in water. It is one of the strongest acids, so it tends to exist in ores with many other metals in nature.

The specific heat that rhodium has is 0.242 J/g K and even has an electronegativity of 2.28 on the Pauling scale. The heat of fusion and vaporization is 26.59 kJ mol and 493 kJ mol, respectively. Further, the electron configuration for this electron is [Kr] 4d85s1.

It has only one stable isotope in nature which is 103Rh. Several other (unstable) isotopes range from 93Rh to 117Rh. However, there are no major uses of the Rhodium isotopes.

Rhodium is not really toxic; however, it is advised that all rhodium compounds should be treated as highly toxic and carcinogenic.

These are highly reflective, extremely resistant to corrosion, and not attacked by acids. The metal is highly reflective of light. Its atomic number is 45 on the periodic table. As one of the rarest and most expensive metals known to mankind, it is extremely hard to find and very expensive.

It is even used for chemical reactions that can possibly have many industrial applications. It is the decay product of uranium and is considered isolated from nuclear waste. Rhodium and ruthenium are two precious metals that are produced as a small percentage of the fission products from the nuclear fission of uranium.

Physical Properties Of Rhodium

The appearance of rhodium is silvery and shiny, and it is in the form of a solid at room temperature.

It will not react easily with air, water, and many other chemical compounds if you keep it out. This is because it does not make chemical bonds. Rhodium metal is notably inert to reaction with acids, including aqua regia, a mixture of hydrochloric acid and nitric acid, which are the two strongest acids.

If you get pure rhodium, then it will be non-toxic, but when it is unstable, meaning when it is a part of a compound, then it can be highly toxic.

It has a lower density than other platinum group metals, such as palladium and ruthenium. It has got a higher melting point than platinum, whereas the boiling point is similar to platinum.

Rhodium's melting point is 3,567 F (1,964 C), and boiling point is 6,683 F (3,695 C). Rhodium has a density of 7.17 oz per cu in (12.41 g per cu cm). At the same time, it is an extremely conductive metal.

Uses Of Rhodium

There are several uses of rhodium; some can be notable in general, and some are exclusive to science and industrial use. Rhodium has multiple applications in the making of precious jewelry.

It is used to coat white gold that is silver in appearance. The shine of the resulting metal will also be enhanced and protected if it is used.

Do you know what makes white gold so different from yellow gold? If you talk about pure gold, it will remain yellow if you add silver and copper to it. Whereas in white gold, the copper gets replaced with palladium and nickel.

Rhodium is also used as an alloying agent for hardening and improving the corrosion resistance of other members of its family, including platinum and palladium.

A coating of optical fibers covers the transition metal. Chemicals within catalytic converters cause reactions to happen at a faster pace. The major use of rhodium is in catalytic converters for cars. Rhodium is also used as a catalyst in the chemical industry; it is used in the making of acetic acid, nitric acid, and hydrogenation reactions.

This metal also has many other industrial applications and is used in the manufacturing of components for various things like aircraft, scientific equipment, and more.

FAQs

Why is rhodium more expensive than gold?

Rhodium is among the rare and precious metals, just like gold, but even rarer. If you compare the two according to the market price of gold, rhodium is twice as valuable as gold.

Where is rhodium found in nature?

Rhodium is the rarest non-radioactive metal in North and South American river sands. You can also find it in copper-nickel sulfide ores in Ontario, Canada.

Is rhodium dangerous?

There are almost no reported cases of a human being affected by this element in any way. In its purest form, rhodium is considered safe. However, when it is not pure, it is advised that all rhodium compounds be regarded as highly toxic.

What is the density of rhodium?

Rhodium has a density of 7.17 oz per cu in (12.41 g per cu cm).

What products contain rhodium?

The rhodium can appear in several items such as jewelry, aircraft engines, laboratory crucibles, furnace coils, and the most common use is in the catalytic converters of vehicles.

How did rhodium get its name?

Rhodium is said to have got its name from the Greek word 'rhodon,' meaning 'rose,' because of its red color in the state that which it was first found. The red color is seen in many of its compounds.

Is rhodium flammable?

Although rhodium is a non-combustible solid, it can burn if it is in the form of a powder or dust.

Does rhodium conduct electricity?

Rhodium compounds conduct electricity as it has a conductivity of 38% IACS.

Is rhodium plating toxic?

No, rhodium plating is hypoallergenic, and you won't suffer skin reactions by wearing rhodium-plated jewelry.

What is the normal phase of rhodium?

Rhodium is usually solid in its natural state.

Why is rhodium so precious?

Rhodium is an incredibly rare and precious metal because it is not easily found, is very limited, and yet its properties make it very useful. Thus, the low supply but high demand make it precious.

What is the rarest metal on Earth?

One of the rarest, most expensive, and most precious metals found on Earth is rhodium. 

What is the most expensive metal in the world?

Rhodium is widely considered to be the most expensive metal. 

Can rhodium rust?

Rhodium does not tarnish and is corrosion-resistant, and does not cause rust.

Who produces rhodium?

The main or biggest exporter of rhodium is South Africa, which produces about 80% of the overall amount according to the data from 2010, and the second is Russia.

What country has the most rhodium?

It is a metal from the platinum group, and South Africa is the country that has most of the rhodium deposits.