To determine the moles of copper we must use its atomic weight. This value can be found in the periodic table. The atomic weight of copper is 63.546g/mol, so the moles of copper will be:
[tex]\begin{gathered} \text{Moles Cu= Given g of Cu }\times\frac{1molCu}{Atomic\text{ weight Cu, gCu}} \\ \text{Moles Cu=51.226gCu}\times\frac{1molCu}{63.546\text{gCu}}=0.806 \end{gathered}[/tex]The moles of Cu in 51.226g are 0.806 mol