Here we are going to study the classification of electronic materials. And you can also say difference between conductor, insulator and semiconductor, Then let’s start this topic.
Depending on the number of valence electrons, materials are classify in to three types.
- Valency < 4 ⇒ Conductor/ metals
- Valency = 4 ⇒ Semiconductor
- Valency > 4 ⇒ Insulator / non – metals
In the word – If valency less than 4 then it will be conductor or metals and if valency is greater than 4 then it will be insulator or non-metals and if valency is equal to 4 then it will be semiconductor.
Conductor materials
Definition of conductor – If valency of an atom in a material is < 4, then those materials are call conductor / metals.
These materials have < 4 electrons in their outer most orbit. So, this type of materials have more free electrons as compare to insulators and semiconductors.
These materials can conduct electricity easily hence, in this materials have less resistivity. So the example is – Aluminium, silver, copper, sodium.
For energy band diagram of conductor, insulator and semiconductor click here.
For types of electron emission click here.
Insulator materials
Definition of insulator – A material do not easily transmit energy, such as electric current or heat. materials such as wood, plastic, and ceramics are insulators. fiberglass in an example of a heat insulator.
These material have more than 4 number of electron in their outer most orbit. Hence in this materials have less number of free electrons as compare to conductor and semiconductor.
These materials can’t conduct electricity. So, its resistivity is high. So the Example is – wood, plastic, non-metals.
Semiconductor material
Definition of semiconductor – Substance through which electrons flow partially are known as semiconductor.
In this case the materials have equal 4 number of electrons in their outer most orbit. So, this materials have moderate (equal) number of free electrons. Hence, these materials do not conduct electricity at room temperature.
But if impurity is add to it, then it will conduct electricity. Its resistivity lies between conductor and insulator. So the Example is – silicon, germanium.
Thus, it is the three types of material.
For what is semiconductor and its types click here.
Some important short notes :
Definition valency
It is defined as the number of electrons present in the outer most orbit / shell in a atom so it is known as valency.
Valence electrons definition
The electrons which are revolving around the nucleus in the outer most orbit are call valence electron.
What is free electrons ?
The electrons present in the outermost orbit gain sum amount of energy and return free from the force of nucleus those electrons are called as free electrons.
In the above article we study about classification of electronic materials. The resistivity in the conductor is low due to which it is called a good conductor so the current passes through it comfortably and the insulator has very high resistivity due to which current does not pass through it. Similarly semiconductor act like insulator and its resistivity is between conductor and insulator.
This is the basic concept in electronics and I think the basic concept should be clear to you because in all the competitive exam the question comes from basic like diploma, B. Tech, GATE. So I share this concept. Thank you