Conduction
Definition and meaning of Conduction in chemistry.
Conduction is the transfer of heat or electric charge directly through a material. It happens through direct physical contact between tiny particles. The bulk material itself does not move from one place to another.
In more detail
In thermal conduction, heat energy flows from hotter regions to cooler regions. When atoms heat up, they vibrate faster and bump into their neighbors. These frequent collisions pass the thermal energy along the physical material.
Metals contain loose electrons that also carry heat energy very efficiently. Electrical conduction transfers electric charge instead of transferring thermal energy. An applied voltage pushes charged particles completely through a given substance.
In solid metals, free electrons drift around to carry the electric current. Chemists refer to this specific process as electronic conduction. In melted salts or liquid water solutions, ions move to carry the current.
Ions are simply atoms or molecules that hold a positive or negative charge. This physical movement of ions is called ionic or electrolytic conduction. A material's overall conductivity depends heavily on its available charge carriers.
It also depends on exactly how freely those charge carriers can move. This rule explains why solid metals conduct electricity so incredibly well. Their outermost electrons can drift freely throughout the entire solid crystal structure.
Solid salts have tightly locked ions that cannot move around the lattice. As a direct result, solid salts cannot conduct electricity at all. Students often forget that conductivity requires particles that can physically move.
Key facts
| Field | Physical Chemistry |
|---|---|
| Main types | Thermal conduction and electrical conduction |
| Charge carriers in metals | Free moving electrons |
| Charge carriers in liquids | Positive and negative ions |
| SI unit of electrical conductivity | Siemens per meter (S/m) |
| Requirement for conduction | Mobile particles that can carry energy or charge |
Sodium chloride is regular table salt with the chemical formula NaCl. When it is solid, its positive Na+ and negative Cl- ions are locked in place. They form a rigid crystal lattice that completely blocks any electrical current. As a result, solid table salt is a very poor electrical conductor. Heating the salt until it melts changes this physical behavior completely. The extreme heat breaks the rigid lattice apart into a moving liquid. The sodium and chloride ions can now drift freely through the liquid. If you apply a voltage, these mobile ions flow toward the electrical poles. This flowing movement turns molten salt into an excellent electrical conductor.
Frequently asked questions
What is the difference between electronic and ionic conduction?
Electronic conduction moves charge using electrons without moving the bulk material. Ionic conduction moves charge by physically moving ions through a melted salt or liquid solution.
Why does pure water conduct electricity poorly?
Pure water has very few ions available to carry an electrical charge. Dissolving a salt into the water adds mobile ions that greatly increase its electrical conductivity.
Can a material conduct heat but not electricity?
Yes, many materials can conduct heat through vibrating atoms without conducting electricity. For example, diamond is an excellent heat conductor but blocks electrical current completely.