The copper atom has one lone electron in its outer shell, which can easily be pulled away from the atom. When you receive a shock from static electricity, tiny particles called electrons actually move between your body and some other object.
All matter is made of atoms, and all atoms have electrons.
Electrons occupy a space that surrounds the atoms nucleus. For most atoms, the outermost shell does not contain its maximum number of electrons. Some atoms, such as copper, have only one electron in its outer shell. Because there's only one electron in the copper atom's outer shell, it's not strongly attached to the atom. In other words, it is easily pulled away.