1. **State the problem:** Convert 63.55 grams of copper (Cu) to moles. 2. **Formula used:** The number of moles is calculated by dividing the mass of the substance by its molar mass. $$\text{moles} = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}}$$ 3. **Important rule:** The molar mass of copper (Cu) is approximately 63.55 g/mol. 4. **Calculate moles:** $$\text{moles} = \frac{63.55}{63.55}$$ 5. **Simplify the fraction:** $$\text{moles} = \frac{\cancel{63.55}}{\cancel{63.55}} = 1$$ 6. **Interpretation:** 63.55 grams of copper corresponds to exactly 1 mole of copper atoms. **Final answer:** $$\boxed{1 \text{ mole of Cu}}$$