WTF? They use gold thread to bond the bare microchip to the pins inside the packaging, supposedly because it's a better conductor. It isn't exposed to air since it's inside the sealed package.
Look at wiki - i gave you link - don;t argue with physics 
They used to work with gold then aluminium before using copper (hello intel coppermine cpus ?) because those metals do not diffuse into silicon substrate as parasite ions. Copper needs extra treatment that has been discovered later.
Learning probably not killed anybody yet