ELECTROCHEMISTRY LESSON ONE (A LEVEL)

Modes of conduction of substances, common terms used in electrolysis

## Modes of Conduction in Substances:

There are three main modes of conduction observed in different substances:

**1. Metallic Conduction:**

* **Description:** Involves the movement of **free electrons** within a metallic lattice. These electrons are not bound to any specific atom and can move freely throughout the metal.
* **Examples:** Metals like copper, aluminum, and silver are good conductors of electricity due to the presence of a large number of free electrons.

**2. Ionic Conduction:**

* **Description:** Occurs in **electrolytes** (molten salts or ionic solutions) where **ions** move through the solution carrying the charge.
* **Examples:** Aqueous solutions of salts like NaCl or molten salts like NaCl (liquid) conduct electricity through the movement of Na⁺ and Cl⁻ ions.

**3. Electronic Conduction in Semiconductors:**

* **Description:** Involves the movement of both **electrons** and **holes** (the absence of an electron in the valence band) in semiconductors. The conductivity can be controlled by applying external factors like doping or electric fields.
* **Examples:** Materials like silicon and germanium exhibit semiconducting behavior, where their conductivity can be tailored for various applications in electronics.

## Common Terms Used in Electrolysis:

* **Electrolyte:** A substance that conducts electricity due to the presence of free ions.
* **Electrode:** An electrical conductor that is in contact with an electrolyte.
* **Anode:** The positive electrode where oxidation occurs.
* **Cathode:** The negative electrode where reduction occurs.
* **Electrolysis:** The process of using electrical energy to drive a non-spontaneous chemical reaction.
* **Electrolysis products:** The substances formed at the electrodes during electrolysis.
* **Electrolytic cell:** A device used to carry out electrolysis, consisting of electrodes, an electrolyte, and a power source.
* **Aqueous electrolysis:** Electrolysis involving water as the electrolyte.
* **Electroplating:** The deposition of a metal onto the cathode from a metal-containing solution.
* **Electrorefining:** The purification of a metal by removing impurities that go into the solution during electrolysis.

Understanding these terms and the different modes of conduction is crucial for comprehending the principles and applications of electrolysis in various fields like electroplating, battery technology, and chemical production.