In ancient times, people in Egypt and the Americas used platinum for jewelry and decorative pieces, often times mixed with gold. The first recorded reference to platinum was in when Julius Scaliger, an Italian physician, described a metal found in Central America that wouldn't melt and called it " platina ," meaning "little silver. In , British scientist Charles Wood published a study introducing platinum as a new metal and described some of its attributes and possible commercial applications, according to Peter van der Krogt a Dutch historian.
Then, in , Spanish scientist and naval officer Antonio de Ulloa published a description of a metal that was unworkable and unmeltable. He originally wrote it in , but his papers were confiscated by the British navy. Back in the 18th century, platinum was the eighth known metal and was known as "white gold," according to van der Krogt. Previously known metals included iron, copper, silver, tin, gold, mercury and lead.
In the early s, friends and colleagues William Hyde Wollaston and Smithson Tennant, both British chemists, produced and sold purified platinum that they isolated using a technique developed by Wollaston, according to van der Krogt This technique involves dissolving platinum ore in a mixture of nitric and hydrochloric acids known as aqua regia.
After the platinum was separated from the rest of the solution, palladium, rhodium, osmium, iridium, and later ruthenium were all discovered in the waste. Today, platinum is still extracted using a technique similar to that developed by Wollaston. Samples containing platinum are dissolved in aqua regia, are separated from the rest of the solution and byproducts, and are melted at very high temperatures to produce the metal. Related Content Science Features. Gold-digging Astrophysicists.
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I think this is a nice succinct explanation. You always have this trade-off in reactions, but in gold, you don't get much energy in the new compound formation, and you're losing the gold-gold interactions. Relativistic effects account for gold's lack of reactivity. Gold has a heavy enough nucleus that its electrons must travel at speeds nearing the speed of light to prevent them from falling into the nucleus.
This relativistic effect applies to those orbitals that have appreciable density at the nucleus, such as s and p orbitals. These relativistic electrons gain mass and as a consequence, their orbits contract.
As these s and to some degree p orbits are contracted, the other electrons in d and f orbitals are better screened from the nucleus and their orbitals actually expand. Since the 6s orbital with one electron is contracted, this electron is more tightly bound to the nucleus and less available for bonding with other atoms. The 4f and 5d orbitals expand, but can't be involved in bond formation since they are completely filled.
This is why gold is relatively unreactive. If you'd like to see the formulas and math behind this it's not all that complicated see here. Also note that similar arguments explain mercury's anomalous properties.
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