The atomic number 29 (containing 99% copper) is pre-made into a thick plate because the anode, the pure copper is formed into a skinny sheet because the cathode, and therefore the mixed solution of oil of vitriol and copper sulphate is employed because the electrolyte. After electrification, copper dissolves from the anode into copper ions (Cu) and moves to the cathode. After reaching the cathode, electrons are obtained and pure copper (also called electrolytic copper) is precipitated at the cathode. Impurities in atomic number 29, like iron and zinc, which are more active than copper, will dissolve along with copper as ions (Zn and Fe). Since these ions are less likely to be precipitated than copper ions, the precipitation of those ions on the cathode may be avoided as long because the potential drop is correctly adjusted during electrolysis. Impurities less reactive than copper, like gold and silver, are deposited on the underside of the cell. The copper plates produced during this way, called "electrolytic copper", are of extremely top quality and may be accustomed make electrical products.