Question

Why is Gold unreactive?

Answer 1

The electronic configuration of Gold would be:

$\left[\mathrm{Xe}\right]4{\mathrm{f}}^{14}5{\mathrm{d}}^{10}6{\mathrm{s}}^1$

• When considering relativistic effects, gold is the go-to element. Its $6\mathrm{s}$electron travels at a breakneck pace.
• The $1\mathrm{s}$electron in gold runs at roughly $57.7\%$the speed of light, thus the $6\mathrm{s}$electron must be pretty fast.
• This fast $6\mathrm{s}$ electron is therefore attracted to the nucleus more strongly than expected, and the $6\mathrm{s}$ orbital contracts (relative to without relativistic effects).
• The core $5\mathrm{d}$and $4\mathrm{f}$ orbitals extend to preserve the orthogonality of all orbitals.
• As a result, the 6s electron becomes less accessible for bonding than expected and has an energy difference with numerous incoming reactants, rendering gold generally unreactive.