We may finally know why gold stays so shiny
Gold doesn’t tarnish like other metals mauritius images GmbH/Alamy Silver goes dull, copper turns green and iron rusts, but gold always stays shiny. Why this is the case has remained a mystery, but researchers may have finally figured out what makes the valuable metal so resistant to change and how to tarnish it. Gold is chemically inert, meaning that it doesn’t react with molecules from its surroundings, such as oxygen in the air. This is great news for jewelry, but it limits gold’s usefulness in chemistry, where researchers think it could be a useful catalyst – if only it could be nudged out of its inertness. Matthew Montemore and Santu Biswas at Tulane University in Louisiana investigated a phenomenon called reconstruction, which happens when a piece of gold is cut, creating a new surface. “The atoms just hate being on a surface so much that they completely rearrange,” says Montemore. Often, they rearrange into a pattern resembling repeating hexagons, then don’t shuffle further because their energy is low in this arrangement. Reconstruction isn’t common among …
