Cells

Electrolyte – molten or dissolved metal compounds that conduct electricity. When electrolytes conduct electricity, ions move.

Electrode – most electrodes are metals or graphite. When metals conduct electricity, valence electrons move from ion to ion, from the negative to positive electrode. When graphite conducts, the delocalised electrons between the layers can flow. The two electrodes are called the cathode (which is negatively charged and attracts cations) and the anode (which is positively charged and attracts anions). Reduction occurs at the cathode and oxidation occurs at the anode. The mobile ions of the electrolyte carry the current between the electrodes. Graphite electrodes must be replaced periodically because graphite will react with oxygen to form CO2.

Electrochemical Cells – produce electricity spontaneously via a chemical reaction (redox) between two metals.

• When two metals of different reactivity are connected electrically in a complete circuit with a conducting wire and an electrolyte, electrons flow from the more reactive metal to the least reactive
• The electron flow is called current, and the energy transfer from the higher to lower reactivity metals is called the voltage.
• The greater the difference in reactivity between the two metals making up the electrodes, the greater the energy transfer and therefore greater voltage of the
• A dry cell uses a damp paste of ionic material (salt bridge) between the electrodes instead of a liquid electrolyte.
• More than one cell connected together is called a battery.
• The more reactive metal is always the negative