What is it inside their atoms that lets gold shrug the world off when iron cannot?

Leave an iron nail outside and within weeks it turns crumbly and orange. But a gold ring can sit buried in the ground for three thousand years and come out as bright as the day it was made. Both are metals. Both meet the very same damp air. So the difference cannot be in the air. It must be hiding inside the atoms themselves. What is a gold atom doing that an iron atom is not?