It's shiny, metallic and melts easily into bars, coins or jewelry. It will not rust, corrode or decompose. Gold, element number 79 in the Periodic Table of the Elements, is one of the most recognizable in the group. It is malleable and shiny, making it a good material for metalworking.
Chemically speaking, gold is a transition metal. Transition metals are unique, because they can bind to other elements using not only their outermost layer of electrons (the negatively charged particles that revolve around the nucleus of an atom), but also the two outermost layers. This occurs because the large number of electrons in transition metals interferes with the usual ordered classification of electrons in layers around the nucleus. In the Book of Exodus, the golden calf is a symbol of idolatry, while in the Book of Genesis, Abraham was said to be rich in gold and silver, and Moses was ordered to cover the mercy seat of the Ark of the Covenant with pure gold.
Examples include the aqua regia process, which involves dissolving the alloy in strong acids and then recovering the gold electrolytically through the Wohlwill process, which allows the removal of all residual platinum group metals and, therefore, the delivery of extremely pure gold. Some gold compounds exhibit aurophilic bonds, which describe the tendency of gold ions to interact at distances that are too long to be a conventional Au-Au bond, but shorter than the van der Waals bond. The proportion of gold in the alloy is measured in carats (k), with 24 carats (24k) being pure gold (100%), and proportionally lower lower carat numbers (18k %3D 75%). Gold bars kept in Fort Knox and elsewhere in the world are considered 24 karat gold with 99.95 percent purity.
Fourteen- and eighteen-carat gold alloys with silver alone appear greenish-yellow in color and are called green gold. Common colored gold alloys include the distinctive eighteen-carat rose gold created by the addition of copper. Usually, gold is created from platinum, which has one less proton than gold, or from mercury, which has one more proton than gold. Gold also dissolves in mercury, forming amalgam alloys, and since gold acts simply as a solute, it is not a chemical reaction.
Gold has only one stable isotope, 197Au, which is also its only natural isotope, so gold is a mononuclide and monoisotopic element. The value chain for industrial gold recycling, in particular, is longer, comprises more players and is more complex than the value chain for recycling high-value gold. It should be obvious from this process that it currently costs much more money to create non-radioactive gold than it could earn by selling gold. World consumption of new gold produced is around 50% in jewelry, 40% in investments and 10% in industry.
As metals are added to gold during jewelry making, gold becomes less fine and the carat number decreases. Gold played a role in Western culture, as a cause of desire and corruption, as told in children's fables such as Rumpelstiltskin, where Rumpelstiltskin turns hay into gold for the peasant's daughter in exchange for her daughter when she becomes a princess and the theft of the hen that lays golden eggs in Jack and Beanstalk. The benefit of using gold over other connector metals such as tin in these applications has been debated; audiovisual experts often criticize gold connectors as unnecessary to most consumers and are seen simply as a marketing tactic.