At the anode of the galvanic cell, copper atoms spontaneously leave the electrode and enter the solution as Cu2+ ions. The electrons that are left behind give the anode a slight negative charge. (We say the anode has a negative polarity.) At the cathode, electrons spontaneously join Ag+ ions to produce neutral atoms, but the effect is the same as if Ag+ ions become part of the electrode, so the cathode acquires a slight positive charge. (The cathode has a positive polarity.) During the operation of the cell, the amount of positive and negative charge on the electrodes is kept small by the flow of electrons (an electric current) through the external circuit from the anode to the cathode when the circuit is complete. In fact, unless electrons can flow out of the anode and into the cathode, the chemical reactions that occur at their surfaces will cease.