Gold is the 79th chemical element on the Periodic Table of Elements, is among the most well-known. It has symbol Au (from Latin aurum ‘gold’ which means “shining dawn” or “sunrise glow.”) and atomic number 79. The modern word gold comes from Sanskrit word Jval and Anglo-Saxon word gold meaning “yellowish green.”
History
It is an exquisite and highly prized metal, been around for at least 5500 years. Gold can be found all over the ancient globe, from Eastern Europe to the Middle East to Egyptian Pharaohs’ graves. Five thousand years ago, the huge Nile River was the key to the ancient Egyptian empire. There was a dazzling yellow metal running down the river, which was the element of gold. The Egyptians immediately accepted this visually enticing gem, discovering that because it was naturally pure and flexible, it needed no processing to be transformed into mesmerising ornamentation.
Gold plays an important role in Australian history. Australia’s population increased in the late nineteenth century as a result of the thriving gold rush. According to the Australian government, the country continues to mine for the metal due to its widespread resources. Gold comes from China, Australia, Russia, the United States, Canada, Peru, and South Africa.
Gold is occasionally discovered alone in nature, although it is frequently found in combination with silver, quartz (SiO2), calcite (CaCO3), lead, tellurium, zinc, or copper. Gold has a constant lustre. Moreover, Gold will not tarnish, corrode or oxidise. All other metals darken or turn yellowish after oxidising or reacting with other substances.
Each tonne of seawater contains around 1 milligram of gold, but extracting it now costs more than the gold itself. It is thought that all of the gold that has been refined could be placed in a cube 20 metres on each side.
| A karat of gold is 1/24th of a portion of pure gold. The word karat comes from carob seeds, which were used in ancient Asian bazaars to measure the weight of gold. Pure gold is 24 karats, while 18-karat gold is 75% gold, 14-karat gold is 58.5% gold, and 10-karat gold is 41.7% gold. Most gold is 14k or 10k because high-purity gold is soft and easily scratched and deformed. The remaining percentage of metal in karat gold usually is silver, but can be copper, platinum, nickel, iron, or cadmium. |
Properties
Gold is a ‘noble’ metal, which means it will not corrode or lose its lustre. Other noble metals include ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, mercury, rhenium, and copper.
Gold is the most malleable and ductile of any known metal. Gold is malleable as it can be hammered paper thin and it will not shatter. A single ounce of gold can be pounded into a sheet around 5 metres wide. Thin sheets of gold, known as gold leaf, are commonly used in arts and crafts for gilding. One sheet of gold leaf can be as thin as 0.000127 millimetres, or around 400 times thinner than a human hair.
The precious metal may be simply shaped to fit on or build practically any statue or piece of art. To that end, gold represents indestructibility, eternity, and adaptability. Gold’s colour does not fade with the passage of time or exposure to natural factors. A gold coin or anything discovered after a thousand years will emerge from the ground in the same unspoiled condition as when it was first buried centuries or millennia before.
Pure gold is soft and is usually alloyed with other metals, such as silver, copper, platinum or palladium, to increase its strength. Gold alloys are used to make jewellery, decorative items, dental fillings and coins.
Karat
The amount of gold in an alloy is measured with a unit called a karat. Most gold jewellery is not created from pure gold. The amount of gold in a necklace or ring is measured using the karat scale.
Gold bars stored at Fort Knox and other locations throughout the world are regarded 99.95 percent pure, 24-karat gold.
As metals are added to gold during jewellery production, the gold becomes less fine and the number of karats decreases. For example, 12 karat gold is 50% gold and 50% alloys by weight.
Gold is a good conductor of heat and electricity and does not tarnish when it is exposed to the air, so it can be used to make electrical connectors and printed circuit boards. Gold is also a good reflector of infrared radiation and can be used to help shield spacecraft and skyscrapers from the sun’s heat. Gold coated mirrors can be used to make telescopes that are sensitive to infrared light.
Gold Chemistry
A radioactive isotope of gold, gold-198, is used for treating cancer. Gold sodium thiosulfate (AuNa3O6S4) is used as a treatment for arthritis. Chlorauric acid (HAuCl4) is used to preserve photographs by replacing the silver atoms present in an image.
Gold is a transition metal. Transition metals are remarkable in that they can bond with other elements not only through their outermost electron shell (the negatively charged particles that go around an atom’s nucleus), but also across the outermost two shells. This occurs because the enormous number of electrons in transition metals disrupts the normal orderly sorting of electrons into shells surrounding the nucleus.
Pure gold will melt at 1064.43° and boils at 2856.1°. Gold is odourless and tasteless, and flakes can be consumed in foods or beverages.
Trivia
Gold makes up a minuscule proportion of the elements in the known cosmos. Its rarity stems from the enormous amount of energy required for its creation. Gold is generated in stars, but only when they explode in massive supernovas or collide with each other in monstrously strong ways.
As per Glint Insights Network, China is the world’s largest bullion buyer. Next on the list of the greatest gold-consuming nations is India. India is the global leader in gold jewellery consumption, with marriage and social occasions being the most common reasons for purchasing. In 2023, the country imported 781 tonnes of gold.
The largest gold nugget is the ‘Welcome Stranger’ mined in Australia in 1869, weighing in at a staggering 173 pounds (almost 78.5 kilogrammes).
–Dr. Subramanian S Iyer
