Simple! Combine it with another substance, probably a compound, that serves well in an oxidation-reduction reaction. In an oxidation reduction reaction, one substance is oxidized, where the oxidation number is increased. This is what would happen to the copper. Copper has two electrons in it's outer electron shell it is willing to donate, which will cause it to convert to a copper ion with a charge of +2. The other substance that is being combined with copper, will be reduced. When a substance is reduced, it gains electrons. A good example is oxygen. Oxygen is an element that has room for two electrons in it's outer electron shell. Oxygen will gladly accept copper's two electrons; when this happens, oxygen will become negatively charged ion, with a charge of -2. The creation of ions in chemical reactions is the basis of all chemical changes, which produce new substances having different physical and chemical properties.