<h2>2 Cu + 1/2 O2 --> Cu2O + Cu2O + 1/2 O2 --> 2CUO</h2><h2 /><h2 /><h2>Copper is oxidized since it went from being an oxidation number of 0 to +2. </h2><h2 /><h2 />
They have the same number of electrons in their outer shells. Elements in the same group often share similar chemical properties because the outer electrons generally determine a lot of their properties
