2. 1. Rhodium
Discovery date :- 1803
Discovered by :- William Hyde Wollaston
Origin of the name :- The name is derived from the Greek 'rhodon', meaning rose coloured.
Largest producers :- South Africa, Russia, Canada
Rhodium is a chemical element with the symbol Rh and atomic number 45. It
is an extraordinarily rare, silvery-white, hard, corrosion-resistant, and
chemically inert transition metal. It is a noble metal and a member of the
platinum group. It has only one naturally occurring isotope, 103Rh. Naturally
occurring rhodium is usually found as a free metal, as an alloy with similar
metals, and rarely as a chemical compound in minerals such as bowieite and
rhodplumsite. It is one of the rarest and most valuable precious metals.
3. Rhodium is found in platinum or nickel ores together with the other members
of the platinum group metals. It was discovered in 1803 by William Hyde
Wollaston in one such ore, and named for the rose color of one of its chlorine
compounds.
The element's major use (approximately 80% of world rhodium production) is
as one of the catalysts in the three-way catalytic converters in automobiles.
Because rhodium metal is inert against corrosion and most aggressive
chemicals, and because of its rarity, rhodium is usually alloyed with platinum
or palladium and applied in high-temperature and corrosion-resistive
coatings. White gold is often plated with a thin rhodium layer to improve its
appearance while sterling silver is often rhodium-plated for tarnish resistance.
Rhodium is sometimes used to cure silicones; a two-part silicone in which one
part containing a silicon hydride and the other containing a vinyl-terminated
silicone are mixed. One of these liquids contains a rhodium complex.
4. Rhodium detectors are used in nuclear reactors to measure the neutron flux level. Other uses
of rhodium include asymmetric hydrogenation used to form drug precursors and the processes
for the production of acetic acid.
Uses of the Rhodium :-
The major use of rhodium is in catalytic converters for cars (80%). It reduces nitrogen oxides in
exhaust gases.
Rhodium is also used as catalysts in the chemical industry, for making nitric acid, acetic acid
and hydrogenation reactions.
It is used to coat optic fibres and optical mirrors, and for crucibles, thermocouple elements
and headlight reflectors. It is used as an electrical contact material as it has a low electrical
resistance and is highly resistant to corrosion.
5. 2. Platinum
Discovery date :- 1735
Discovered by :- Antonio de Ulloa
Origin of the name :-The name is derived from the Spanish 'platina', meaning little silver.
Largest producers :- South Africa, Russia, Canada
Platinum is a chemical element with the symbol Pt and atomic number 78. It is a dense,
malleable, ductile, highly unreactive, precious, silverish-white transition metal. Its name is
derived from the Spanish term platino, meaning "little silver".
Platinum is a member of the platinum group of elements and group 10 of the periodic
table of elements. It has six naturally occurring isotopes. It is one of the rarer elements in
Earth's crust, with an average abundance of approximately 5 μg/kg. It occurs in some
nickel and copper ores along with some native deposits, mostly in South Africa, which
accounts for 80% of the world production. Because of its scarcity in Earth's crust, only a
few hundred tonnes are produced annually, and given its important uses, it is highly
valuable and is a major precious metal commodity.
6. Platinum is one of the least reactive metals. It has remarkable resistance to corrosion,
even at high temperatures, and is therefore considered a noble metal. Consequently,
platinum is often found chemically uncombined as native platinum. Because it occurs
naturally in the alluvial sands of various rivers, it was first used by pre-Columbian
South American natives to produce artifacts. It was referenced in European writings
as early as 16th century, but it was not until Antonio de Ulloa published a report on a
new metal of Colombian origin in 1748 that it began to be investigated by scientists.
Platinum is used in catalytic converters, laboratory equipment, electrical contacts and
electrodes, platinum resistance thermometers, dentistry equipment, and jewelry. Being
a heavy metal, it leads to health problems upon exposure to its salts; but due to its
corrosion resistance, metallic platinum has not been linked to adverse health effects.
Compounds containing platinum, such as cisplatin, oxaliplatin and carboplatin, are
applied in chemotherapy against certain types of cancer.
7. In early 2021, the value of platinum ranged from US$1,055 per troy ounce to
US$1,320 per troy ounce.
Uses of the Platinum:-
Platinum is used extensively for jewellery. Its main use, however, is in catalytic
converters for cars, trucks and buses. This accounts for about 50% of demand
each year. Platinum is very effective at converting emissions from the vehicle’s
engine into less harmful waste products.
Platinum is used in the chemicals industry as a catalyst for the production of
nitric acid, silicone and benzene. It is also used as a catalyst to improve the
efficiency of fuel cells.
8. The electronics industry uses platinum for computer hard disks and
thermocouples.
Platinum is also used to make optical fibres and LCDs, turbine blades,
spark plugs, pacemakers and dental fillings.
Platinum compounds are important chemotherapy drugs used to
treat cancers.
9. 3. Gold
Discovery date :- 3000 BC
Discovered by :- Ancient Mesopotamians
Origin of the name :- The name is the Anglo-Saxon word for the metal and the
symbol comes from the Latin ‘aurum’, gold.
Largest producers :- South Africa, The United States, Australia and China.
Gold is a chemical element with the symbol Au (from Latin: aurum) and atomic number 79,
making it one of the higher atomic number elements that occur naturally. In a pure form, it is a
bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a
transition metal and a group 11 element. It is one of the least reactive chemical elements and is
solid under standard conditions. Gold often occurs in free elemental (native) form, as nuggets
or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the
native element silver (as electrum), naturally alloyed with other metals like copper and
palladium and also as mineral inclusions such as within pyrite. Less commonly, it occurs in
minerals as gold compounds, often with tellurium (gold tellurides).
10. Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of
nitric acid and hydrochloric acid), which forms a soluble tetrachloroaurate anion.
Gold is insoluble in nitric acid, which dissolves silver and base metals, a property
that has long been used to refine gold and to confirm the presence of gold in
metallic substances, giving rise to the term acid test. Gold also dissolves in alkaline
solutions of cyanide, which are used in mining and electroplating. Gold dissolves in
mercury, forming amalgam alloys, and as the gold acts simply as a solute this is not
a chemical reaction.
A relatively rare element,[6][7] gold is a precious metal that has been used for
coinage, jewelry, and other arts throughout recorded history. In the past, a gold
standard was often implemented as a monetary policy, but gold coins ceased to be
minted as a circulating currency in the 1930s, and the world gold standard was
11. A total of 197,576 tonnes of gold exists above ground, as of 2019. This is equal to
a cube with each side measuring roughly 21.7 meters (71 ft). The world
consumption of new gold produced is about 50% in jewelry, 40% in
investments, and 10% in industry. Gold's high malleability, ductility, resistance
to corrosion and most other chemical reactions, and conductivity of electricity
have led to its continued use in corrosion resistant electrical connectors in all
types of computerized devices (its chief industrial use). Gold is also used in
infrared shielding, colored-glass production, gold leafing, and tooth
restoration. Certain gold salts are still used as anti-inflammatories in
medicine. As of 2017, the world's largest gold producer by far was China with
440 tonnes per year.
12. Uses of the Gold:-
Most mined gold is stored as bullion. It is also, however, used extensively in jewellery, either in
its pure form or as an alloy. The term ‘carat’ indicates the amount of gold present in an alloy.
24-carat is pure gold, but it is very soft. 18- and 9-carat gold alloys are commonly used because
they are more durable.
The metal is also used for coinage, and has been used as standard for monetary systems in
some countries.
Gold can be beaten into very thin sheets (gold leaf) to be used in art, for decoration and as
architectural ornament. Electroplating can be used to cover another metal with a very thin
layer of gold. This is used in gears for watches, artificial limb joints, cheap jewellery and
electrical connectors. It is ideal for protecting electrical copper components because it
conducts electricity well and does not corrode (which would break the contact). Thin gold wires
are used inside computer chips to produce circuits.
13. Dentists sometimes use gold alloys in fillings, and a gold
compound is used to treat some cases of arthritis.
Gold nanoparticles are increasingly being used as
industrial catalysts. Vinyl acetate, which is used to make
PVA (for glue, paint and resin), is made using a gold
catalyst.
14. 4. Osmium
Discovery date :- 1803
Discovered by :- Smithson Tennant
Origin of the name :-The name is derived from the Greek word 'osme', meaning smell.
Largest producers :- South Africa, Russia, Zimbabwe, North and South America.
Osmium (from Greek ὀσμή osme, "smell") is a chemical element with the symbol Os and
atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group
that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest
naturally occurring element, with an experimentally measured (using x-ray
crystallography) density of 22.65 g/cm3. Manufacturers use its alloys with platinum,
iridium, and other platinum-group metals to make fountain pen nib tipping, electrical
contacts, and in other applications that require extreme durability and hardness. The
element's abundance in the Earth's crust is among the rarest, with an abundance of only
50 ppt in the earth's crust. It is estimated to be about 0.6 parts per billion in the universe
and is therefore the rarest precious metal.
15. Uses of the Osmium :-
Osmium has only a few uses. It is used to produce very hard alloys for fountain
pen tips, instrument pivots, needles and electrical contacts. It is also used in
the chemical industry as a catalyst.
16. 5. Palladium
Discovery date :- 1803
Discovered by :- William Hyde Wollaston
Origin of the name :- Palladium is named after the asteroid Pallas, in turn named after
the Greek goddess of wisdom, Pallas.
Largest producers :- Russia, South Africa, the United States, Canada.
Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare
and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde
Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet
of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum,
rhodium, ruthenium, iridium and osmium form a group of elements referred to as the
platinum group metals (PGMs). They have similar chemical properties, but palladium has
the lowest melting point and is the least dense of them.
17. More than half the supply of palladium and its congener platinum is used in catalytic
converters, which convert as much as 90% of the harmful gases in automobile exhaust
(hydrocarbons, carbon monoxide, and nitrogen dioxide) into less noxious substances
(nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics,
dentistry, medicine, hydrogen purification, chemical applications, groundwater
treatment, and jewelry. Palladium is a key component of fuel cells, which react hydrogen
with oxygen to produce electricity, heat, and water.
Ore deposits of palladium and other PGMs are rare. The most extensive deposits have
been found in the norite belt of the Bushveld Igneous Complex covering the Transvaal
Basin in South Africa, the Stillwater Complex in Montana, United States; the Sudbury
Basin and Thunder Bay District of Ontario, Canada, and the Norilsk Complex in Russia.
Recycling is also a source, mostly from scrapped catalytic converters. The numerous
applications and limited supply sources result in considerable investment interest.
18. Uses of the Palladium :-
Most palladium is used in catalytic converters for cars. It is also used in
jewellery and some dental fillings and crowns. White gold is an alloy of gold
that has been decolourised by alloying with another metal, sometimes
palladium.
It is used in the electronics industry in ceramic capacitors, found in laptop
computers and mobile phones. These consist of layers of palladium
sandwiched between layers of ceramic.
Finely divided palladium is a good catalyst and is used for hydrogenation and
dehydrogenation reactions. Hydrogen easily diffuses through heated
palladium and this provides a way of separating and purifying the gas.
19. 6. Silver
Discovery date :- 3000 BC
Discovered by :-Ancient peoples
Origin of the name :- The name is derived from the Anglo-Saxon name, 'siolfur'.
Largest producers :- Peru, China, Mexico and Chile.
Silver is a chemical element with the symbol Ag (from the Latin argentum, derived
from the Proto-Indo-European h₂erǵ: "shiny" or "white") and atomic number 47. A soft,
white, lustrous transition metal, it exhibits the highest electrical conductivity,
thermal conductivity, and reflectivity of any metal.[citation needed] The metal is found in
the Earth's crust in the pure, free elemental form ("native silver"), as an alloy with
gold and other metals, and in minerals such as argentite and chlorargyrite. Most
silver is produced as a byproduct of copper, gold, lead, and zinc refining.
20. Silver has long been valued as a precious metal. Silver metal is used in many
bullion coins, sometimes alongside gold:[4] while it is more abundant than gold, it is
much less abundant as a native metal.[5] Its purity is typically measured on a per-
mille basis; a 94%-pure alloy is described as "0.940 fine". As one of the seven metals
of antiquity, silver has had an enduring role in most human cultures.
Other than in currency and as an investment medium (coins and bullion), silver is used in
solar panels, water filtration, jewellery, ornaments, high-value tableware and utensils
(hence the term "silverware"), in electrical contacts and conductors, in specialized
mirrors, window coatings, in catalysis of chemical reactions, as a colorant in stained
glass and in specialised confectionery. Its compounds are used in photographic and X-
ray film. Dilute solutions of silver nitrate and other silver compounds are used as
disinfectants and microbiocides (oligodynamic effect), added to bandages and wound-
dressings, catheters, and other medical instruments.
21. Uses of the Silver :-
Sterling silver contains 92.5% silver. The rest is copper or some other
metal. It is used for jewellery and silver tableware, where appearance is
important.
Silver is used to make mirrors, as it is the best reflector of visible light
known, although it does tarnish with time. It is also used in dental alloys,
solder and brazing alloys, electrical contacts and batteries. Silver paints
are used for making printed circuits.
22. Silver bromide and iodide were important in the history of photography,
because of their sensitivity to light. Even with the rise of digital photography,
silver salts are still important in producing high-quality images and protecting
against illegal copying. Light-sensitive glass (such as photochromic lenses)
works on similar principles. It darkens in bright sunlight and becomes
transparent in low sunlight.
Silver has antibacterial properties and silver nanoparticles are used in
clothing to prevent bacteria from digesting sweat and forming unpleasant
odours. Silver threads are woven into the fingertips of gloves so that they can
be used with touchscreen phones.
