Past exam of the chemistry A course of the University of Cambridge / 2021 / Paper 2 / A9 / b / i / Solution

Using $M_{\mathrm{Au}}\simeq 196.97\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ and the Avogadro constant, the areal atom count isOne atom occupies each square cell of area $a^2$, so the inferred square lattice spacing isThis uses the given deposited mass and the assumed single square layer; it does not substitute a bulk gold lattice parameter for the measured areal count.