$word_{count}$: 220

Electrochemical cells convert between chemical and electrical energy. Galvanic (voltaic) cells produce electricity from spontaneous reactions (E > 0, $delta_G$ < 0). The anode (negative terminal) undergoes oxidation; the cathode (positive terminal) undergoes reduction. A salt bridge connects the half-cells, allowing ion migration to maintain neutrality. Cell notation: Anode|Anode ion||Cathode ion|Cathode. Electrolytic cells use external electricity to drive non-spontaneous reactions (E < 0, $delta_G$ > 0). The polarity flips: anode is positive (connected to battery's positive terminal), cathode is negative. In BOTH cell types, oxidation occurs at the anode and reduction at the cathode — this never changes. E_{cell}_{standard} = $E_{cathode}$ - $E_{anode}$ (both as reduction potentials from the table). The electrochemical series ranks elements by reduction potential: more positive = stronger oxidising agent, more negative = stronger reducing agent.