Question #4cfe2

1 Answer
Jul 4, 2016

Comparing gold with an alkali metal, the "one outer electron" in gold is much less shielded from the nuclear charge -- therefore more tightly bound.


In an alkali metal, the outer electron surrounds a noble-gas core, e.g. sodium has a neon core and then that one #3s# electron. This noble gas core is esoecially effective at shielding the outer electron from most of the nuclear charge because it is relatively so compact. So the outer electron has only a small net charge binding it to the nucleus.

In gold the electrons immediately below the outer one do not have a noble gas configuration, they are less compact and thus they offer poorer shielding compared with an alkali metal. So the outer electron in gold is rather tightly bound.

However, the less compact electron structure in gold also means some "inner" electrons are potentially available for reaction. So if you do get gold to react, it may go beyond the #+1# oxidation state (usually you get #+3#). The noble gas cores of alkali metals don't do that.