In current electricity, we became to know that the flow of electric charges is the electricity. Again, from the Thermodynamics, we know that the 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 bulb to heat it. This copper and Tungsten are metals and they are used in 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?
Conductivity of a substance
The conductivity is the ability of a substance to transmit heat and electricity. Conductivity is the reciprocal of the resistivity. The 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?
A metal has 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 electron sea model which says that metal ions share their electrons to a sea of electrons.
For example: Copper metal has two free electrons (outer electrons). Then Cu2+ is the metal ion which keeps its two free electrons in a virtual sea of electrons by metallic bonding. Since, there are 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 type of molecular structure of metals makes possible for the free electrons to drift from one molecule to another molecule in application of external voltage. This movement of free electrons is nothing but the electric current. This is why metals are good conductors 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 (ability of conduction) is not 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 the pure water cannot conduct electricity. But, salted water can conduct current. It do not follow the same mechanism of metals. Because, it do not have free electrons to flow though 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 cause 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 sea.
- Metals are good conductors of current and heat because of its metallic bonding which provides 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.
- Mobility of free electrons
- Ohm’s law of current electricity
- Kirchhoff’s law of current electricity
- Drift velocity of free electrons