Consider the redox reaction below talking place in certain electro chemical cell: Cu(s)+cu^2+(aq) > Cu^2+(aq) + Cu (s)

cu+2 oxidation whereas Cu reduction.

Explanation:

In the reaction, cu+2 is the place where oxidation occurs because this cupric ion losses electrons  which causes +2 charge on it. we know that oxidation is the loss of electrons and reduction is the gaining of electrons so the Cu is the place or atom at which reduction occurs. Electrochemical cells have two electrodes, which is anode and the cathode. The anode is the electrode where oxidation occurs whereas the cathode is the electrode where reduction takes place.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.