Now that’s a lotta gold!  Gold, copper, and silver are pretty close on the periodic table — in fact, nearly all our precious metals, including nickel and platinum, fit into the furthest right two columns of the transition metals.   That gives them all very similar chemical properties, but one thing it doesn’t really explain is color.

Surprisingly, all of those metals are highly reflective, but don’t really have a color unless you factor in relativistic physics.   Yes, everyone has loved gold for its color since ancient times, but it wasn’t until Einstein arrived that we can explain its two most valuable characteristics.

Atoms have electrons zooming around the nucleus, and they’re a big factor in how the periodic table is arranged.   All of those elements at the right end of the transition metals should have very similar qualities of shininess, conductivity, malleability — which is true.

For copper and gold, however, their electrons are subject to relativistic forces that change their atomic size, making them a filter for light, rather than having a particular color themselves.  Both would be shiny and silver if not for this filtering, and gold’s gold color is also tied to its lack of tarnishing, preventing it from being as reactive as copper and silver to oxidation and other reactions. So, the next time you see a gold coin, marvel at the universal forces that make it look the way it does!