That's the conventional answer, sure, but it's really just pushing the most challenging question back a step from "Why does this piece of paper have value?" to "Why does this piece of shiny metal have value?"
This is usually the point at which goldbugs start talking about how gold doesn't rust or something.
They wouldn't be wrong. I assume gold's value derives from its chemical properties and rareness- all the similar elements (silver, platinum, etc) are similarly high valued. Of course this doesn't mean we should have our economy dependent on the supply of it, but I don't think its hard to see why it is valued.
Gold is a noble metal because given its valance configuration it doesn't combine/react easily with other elements/compounds (its number of electrons are a multiple of eight or something). That's about all the high school chemistry I remember about it.
If Gold were traded as just another commodity and not by the gold fanatics as a 'store of wealth' what would it likely trade at?
Technically ground state gold does not have a full d orbital, but instead the d orbital steals an electron from the preceding s orbital, so instead of 2 s electrons and 7 d, you have 1 s and 8 d. Same with silver and copper. Zinc, cadmium, and mercury, by contrast, have full s and d orbitals.
