Gold can be beaten into a very thin leaf…

Step 1. Volume. $V = \dfrac{1.0\ \text{g}}{19.3\ \text{g/cm}^3} = 0.0518\ \text{cm}^3$.

Step 2. Area. $1.0\ \text{m}^2 \times \left(\dfrac{100\ \text{cm}}{1\ \text{m}}\right)^2 = 1.0 \times 10^{4}\ \text{cm}^2$.

Step 3. Thickness. $\dfrac{0.0518\ \text{cm}^3}{1.0 \times 10^{4}\ \text{cm}^2} = 5.18 \times 10^{-6}\ \text{cm}$. Since $1\ \text{cm} = 10^{7}\ \text{nm}$, this is about $52\ \text{nm}$.