Electronic structure of gold.

Predicted electronic structure: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²4f¹⁴5d⁹.

Current electronic structure: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s¹4f¹⁴5d¹⁰.

The atomic number of gold (Au) is 79. Therefore, its electronic configuration of the ground state should have a total of 79 electrons (add all superscripts).

Au is one of those elements that do not follow the predicted electronic configuration order (other elements are Cu, Ag, Pd, Cr, and Mo). This is because completing the d orbital brings lower energy (less risk of electron repulsion) compared to completing the first orbit.