# If 1 mole of an unknown metal has mass of 63.55 grams, what metal is it?

If one mole of an unknown metal has a mass of $\text{63.55 g}$, then its molar mass is $\text{63.55 g/mol}$. Molar mass is numerically equal to atomic weight.
You can look at the atomic weight of the metals on the periodic table. The atomic weight increases with atomic number. You will see that the element copper has an atomic weight of $\text{63.546}$, which rounds to $\text{63.55}$.