Why are metals good conductors of electricity and heat?

In current electricity, we became to know that the flow of electric charges is electricity. Again, from Thermodynamics, we know that heat is an energy that can flow from one part to another part of a substance. You may have noticed that a wiring of copper (Cu) wire is used in our home or office to supply electricity in different portions of the building. Again, Tungsten filament is used in electrical bulbs to heat them. Copper and Tungsten are metals and they are used for such purposes because they are good conductors of electricity and heat. Now, the question is, Why are metals good conductors of electricity and heat?

Contents in this article:

What is the conductivity of a substance?

Why do metals conduct electricity and heat?
Do all metals conduct electricity?
Why does water conduct electricity?

The Conductivity of a Substance

Conductivity is the ability of a substance to transmit heat and electricity. Conductivity is the reciprocal of resistivity. Thermal conductivity implies the ability of transmission of heat and electrical conductivity refers to the ability of carrying the electric current. These two types of conductivity are discussed in Thermodynamics and current electricity parts respectively.

Why are metals good conductors of electricity?

Metal has a large number of free electrons in it. Free electrons are not bound to any atom. All atoms in a metal share outer electrons. This can be considered as the electron cloud. To describe this, scientists use the electron sea model which says that metal ions share their electrons with a sea of electrons.

For example: Copper metal has two free electrons (outer electrons). Then Cu²⁺ is the metal ion that keeps its two free electrons in a virtual sea of electrons by a metallic bonding. Since there is a large number of atoms (and hence ions) present in a metal, the number of free electrons in the sea of electron is very large. So, the free electrons are shared among the metal ions. These free electrons can move in presence of external energy.

Such a type of molecular structure of metals makes it possible for the free electrons to drift from one molecule to another molecule in the application of external voltage. This movement of free electrons is nothing but the electric current. This is why metals are good conductors of electricity.

Why do metals conduct heat?

Free electrons in metals always vibrate due to lattice vibration or molecular vibration. Again, these electrons are free to move inside the metal after getting some external energy. When a metal is heated, electrons get external energy to move. As a result, these free electrons transfer external heat energy from one molecule to another molecule in the form of vibrational energy. Therefore, metals are good conductors of heat.

Do all metals conduct electricity?

Yes, all metals conduct electricity. But, the conductivity (the ability of conduction) is not the same for all metals. Some of the metals are very good conductors and some metals are not that good. Silver, Gold, Copper and Aluminum are the four best conductors. Again, Silver has the highest electrical conductivity.

But, you should know that some of the non-metals also conduct electricity. For example: Salted water, Silicon, Germanium, etc. non-metal conduct electricity. This property of Silicon and Germanium have huge applications in Electronics.

Why does water conduct electricity?

We know that the water is not a metal. Then it should not conduct electricity. Yes, this is true that pure water cannot conduct electricity. But, salted water can conduct current. It does not follow the same mechanism as metals. Because it does not have free electrons to flow through it. Suppose, a salt NaCl is mixed with pure water. Then NaCl will produce Na⁺ and Cl^– ions after dissolving in the water. Now, the movement of these ions causes the flow of electricity inside the water.

This mechanism is used in electrolysis process. You may know that sea water conducts electricity. This is because of the salt mixed with the water in the sea.

Summary

Metals are good conductors of current and heat because of their metallic bonding which provides a large number of free electrons in it.
All metals do not have equal conductivity. Silver has greater electrical conductivity among the substances.
Non-metals like Silicon, Germanium, salted water, etc. can conduct electricity.

This is all from this article on the electrical conductivity of metals. Hope you understand why are metals good conductors of electricity. If you still have any doubt on this topic you can ask me in the comment section.

Thank you!

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