Copper can lose either one or two electrons during oxidation, depending on the specific oxidation state it adopts.
Copper typically forms two common oxidation states: +1 and +2.
In the +1 oxidation state (Cu+), copper loses one electron. For example, in compounds like copper(I) oxide (Cu2O) or copper(I) chloride (CuCl), copper is in the +1 oxidation state, having lost one electron.
In the +2 oxidation state (Cu2+), copper loses two electrons. Examples of compounds where copper is in the +2 oxidation state include copper(II) oxide (CuO) or copper(II) sulfate (CuSO4).
It's important to note that copper can exhibit other oxidation states in more complex compounds, but the +1 and +2 oxidation states are the most common.