Metallic Conduction

Introduction

The outermost electrons of a metal atom are free to move from one atom to another, unlike polymers that are locked in a chain structure. When you apply current to a wire, new electrons are introduced, causing existing free electrons to move to make room for them, as long as the excess electrons on the other end are carried by the cathode or positive terminal. Heat travels through the metal stirring atoms, which in turn stirs their neighbours, and so on to the other side or end of the wire. This is how metal conduction takes place. Now, let’s dive deeper and learn what a metallic conductor is.

What is a Metallic Conductor?

Metals have some type of chemical bond (due to electrostatic attractive forces), in which the nucleus vibrates, but the outer shell (and sometimes part of the subsequent inner shell) can move at their will if they’re electrons. But these electrons move in the same way that gas or liquid molecules move, and they are free and unaffected by their neighbours.

This behaviour of electrons in metals allows them to conduct heat and electricity with ease. Much easier than most substances (though scientists have developed some superconductors, for example aluminium, niobium, magnesium diboride).

Conduction is the result of applying a potential voltage across a sheet of metal, causing charges to flow in the same direction or in the opposite direction, depending on how you define the charging current (chemists prefer electrons, physicists and engineers use electrons to leave holes left behind; it’s a subtle difference that only makes sense if you’re trying to do load flow calculations.). The motion of free electrons also explains heat conduction.

Thus, metallic conduction is the free random flow of electrons in a metal, which can then be directed to allow the flow of heat and electrical current. Heat always flows downwards from areas of higher temperature, whereas current flows downwards from areas of high potential. 

Mechanism of Metallic Conduction

Valence electrons in metal atoms can move freely. Therefore, metals contain a large number of free electrons that move randomly from one atom to another in all directions. When no electric field is applied to a metallic conductor, free electrons are in thermal equilibrium with the conductor and move randomly across the surface. So the average velocity of electrons in one direction is zero. As this motion does not constitute a net charge transfer through any part of the conductor, there is no current in the conductor.

When an electric field is applied by connecting a battery to a conductor, each electron is affected by electrostatic forces, and the electrons are accelerated in the opposite direction of the electric field. The electrons then gain speed and kinetic energy. However, these electrons collide with atoms (or ions) at the metal’s lattice sites. In a collision, the electrons release their energy to the atoms, which slows them down. However, the electrons are accelerated again due to the electricity and colliding with the atoms. These collisions reduce the average acceleration of the electrons to zero, so the electrons acquire a constant average velocity opposite the direction of the electric field. This speed is called the drift speed and is responsible for passing the current through the conductor.

The random motion of electrons in a metal crystal in the absence of an electric field. Therefore, the average velocity obtained by free electrons in the conductor under the action of the electric field is called the drift velocity.

Which Metal is the Best Conductor of Heat?

The ability of a metal to conduct heat is measured by Thermal conductivity. This property varies by metal type and is important to consider in applications where high operating temperatures are common. In pure metals, thermal conductivity remains about the same with increasing temperature. In alloys, however, the thermal conductivity increases with temperature. Metals that have the highest thermal conductivity are Copper and aluminium, whereas steel and bronze have the lowest. Thermal conductivity is a very important attribute when selecting metals for a specific application. Because copper is an excellent conductor of heat, it is good for heat exchangers, radiators, and even the bottom of pots. Because steel is a poor conductor of heat, it is suitable for high-temperature environments, such as aircraft engines.

Conclusion

Metals that conduct electricity by the flow of electrons are called metallic conductors. It’s just about physical changes, and conductivity decreases with increasing temperature.

The movement of charged particles in metals such as aluminium and copper is called electrons, whereas in other metals, there may be ions or other positive charges.

Example: Copper, silver, aluminium, gold, and steel are some of the most common conductive metals. Of course, silver and gold are effective in behaviour, but they are expensive. Therefore, the most common metal conductor is copper. Factors affecting metal conductors are  the properties and structure of matter, valence electrons per atom, density of matter.