Gold maintains a long-lasting shine because oxygen has difficulty reacting with its surface. Oxidation occurs when oxygen or other elements bond to metal atoms, producing rust or tarnish depending on the metal. How easily oxygen sticks depends on how the metal’s atomic structure holds electrons. Gold keeps its electrons tightly and discourages electron donation, which helps prevent oxidation. Researchers further connect gold’s resistance to how it behaves when cleaved, where a newly exposed surface forms an intricate zigzag or herringbone pattern. This atomic arrangement influences the electronic structure in a way that makes oxidation less favorable than for similar metals.
"Gold sure does glitter, holding a shine far longer than most metals. And now two researchers have explained why. In a paper published today in Physical Review Letters, Santu Biswas and Matthew Montemore of Tulane University reveal the reason gold is harder to oxidize than similar metals. They key, they say, is the same chemical trickery that gives it a beautiful zigzag structure when viewed under a scanning tunneling microscope."
"Oxidation is the process in which oxygen (or another element, such as sulfur) reacts with a metal and attaches to its surface. For iron, we call this buildup of bonded oxygen rust, while oxidation of other metals is referred to as tarnish. How easily oxygen sticks to a metal depends on how well the metal's atomic structure holds onto electrons. In particular, gold treasures its electrons and spurns donations from outside, preserving its shine and making it a cherished material for jewelry and various industrial applications."
"But gold's close clutch of electrons isn't enough to explain just how reticent it is to oxidize. Biswas and Montemore suspected that the additional reason for gold's near invulnerability involved the strange way it behaves when you break it. Cleave a chunk of gold, and the newly exposed face will microscopically re"
Read at www.scientificamerican.com
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