Understanding Conductors, Semiconductors and Insulators in Chemistry.

An object’s ability to transfer electric charge depends upon whether it is made of a conductive or a non-conductive material. For example, when we turn on an electric switch, the bulb glows. It is because a metallic wire is used to transfer electric current to the bulb. But, if a plastic wire or a cotton thread is used in its place, the bulb will not glow. This experiment makes it evident that some objects have the potential to transfer electric charge, while some don’t. According to their abilities, they are classified as Conductors, Semiconductors and Insulators. This article covers their definitions, examples and properties.

What are conductors?

Conductors are materials that allow electricity to flow freely and easily through them. The property of conductors which permits them to conduct electricity is called conductivity. The force required to make the flow of electrons is known as voltage.

How does a conductor work?

The conductivity of a conductor depends on the total number of charged particles present and how far they can move from one place to another. Following are some points about how conductors work:

A conductor has free-moving electrons on its surface, which allow electricity to pass through smoothly.
When an electric charge is transferred through a conductor, it gets distributed across its entire body due to the movement of electrons.
Electric charges continue to spread over a conductor’s surface until the force of repulsion between the electrons in areas of surplus electrons is reduced to the minimum.
When a conductor is brought in contact with another conductor, electric charges get transferred from the first object to the other until the charges are minimised.
Examples of conductors: copper, silver, iron, brass, steel, gold, aluminium, etc. Even human and animal bodies are examples of conductors.

Importance of conductors in our life

Silver is known as the best conductor of electricity as it contains a large number of movable free electrons. It is used in various specialised tools like satellites, solder and electric circuit boards.
Copper is commonly used in household appliances and electrical equipment.
Aluminium is often used in long-distance power lines and electrical appliances.
Nickel is widely used in electric vehicle batteries and power generation facilities.
Graphite is the only non-metal that can conduct electricity. It is used in making electrodes and in car batteries.

What are semiconductors?

Semiconductors are known as the ‘Brains of Modern Electronics’. Semiconductors are elements with a conductivity value between conductors and insulators.

Example: Silicon, Germanium, Arsenide, and the elements near the ‘metalloid-staircase’ on the periodic table.

Types of semiconductors

Semiconductors are divided into two types:

Intrinsic Semiconductors
Extrinsic Semiconductors

Intrinsic semiconductors

Intrinsic Semiconductors are created to be very pure. There is only one particular form of intrinsic semiconductors. Examples: Germanium (Ge), Silicon (Si), etc.

Extrinsic semiconductors

In Extrinsic Semiconductors, conductivity can be improved by adding impurities. The method of introducing an impurity atom into a pure semiconductor is known as doping. Extrinsic semiconductors are divided into two categories –

N-type Semiconductor
P-type Semiconductor
N-type Semiconductor: Impurities like As, Sb and Bi are added into a pure semiconductor like silicon or germanium. As a result, four of the five valence electrons make a bond with the four valence electrons of Si or Ge.
P-type Semiconductor: a pure semiconductor (Si, Ge) is doped with a trivalent impurity like Aluminium, Gallium or Arsenic. As a result, three valence electrons of the impure element make a bond with three of the semiconductor’s four valence electrons.

Comparison between Intrinsic and Extrinsic Semiconductors

Parameters	Intrinsic Semiconductors	Extrinsic Semiconductors
Meaning/ Outline	Semiconductors are in pure form	Semiconductors are doped with impurities.
Production of change carriers	Due to thermal agitation	Mainly due to impurities
Electrical conductivity	Low electrical conductivity	High electrical conductivity
Temperature	Low operating temperature	High operating temperature
Behaviour at 0 kelvin	Fermi level stands between conduction and valence bands	In N-type semiconductors, the Fermi level lies close to the conduction band. In P-type semiconductors, the Fermi level lies near the valence band.
Examples	Silicon, Germanium	Si and Ge are doped with Al, Ga, P etc.

Importance of semiconductors in our life

Semiconductors are used in temperature sensors of air conditioners.
Semiconductors are used in designing logic gates, digital circuits, and analogue circuits like oscillators and amplifiers.
Semiconductors are used in solar plates.
Semiconductors are used in 3D printers and microchips.
Semiconductor devices are used in computers, calculators, mobile phones and other electronic gadgets.

What are insulators?

Insulators are non-metal elements that have high resistance to the transmission of electricity. These materials stop electrons from moving freely from one element to another.

Examples: glass, plastics, wool, cotton, rubber, pure water etc.

How does an insulator work?

If an electric charge is applied to an insulator, it remains in the applied area and does not spread throughout the element’s body.

Methods for charging insulators:

Induction
Rubbing with other materials

Importance of insulators in our life

Ceramic materials (insulators) are often used in wire holders and coating in high voltage power systems to restrict wires from conducting electricity.
Dry cotton is a frequently used material in cloth tapes that insulates electrical wires and keeps people safe and secure.
Fibreglass wire is an excellent insulator used in high voltage power systems like ovens or furnaces.
Glass is typically used as an insulator in power lines.
Rubber is an excellent insulator. Electricians use rubber gloves and shoes to protect themselves against electric shocks. Rubber is also used in switchboards and electrical sheathing.

Comparative analysis between conductors, semiconductors, and insulators

Parameters	Conductors	Semiconductors	Insulators
Definition	A substance that allows electric charge to pass freely through it	A material whose conductivity lies between conductors and insulators	A substance that does not permit the flow of electric current
Relationship with Temperature	With an increase in temperature, its resistance increases	With an increase in temperature, its resistance decreases	With an increase in temperature, its resistance decreases
Conductivity	High conductivity	Intermediate conductivity	Low conductivity
Reason of conduction	Due to the presence of free electrons in metal bonding	Due to the movement of electrons and holes	No conduction, as there are no free electrons
Conductivity value	Very high, i.e. 10-⁷ MHO/M	Between 10-⁷ MHO/M to 10-¹³ MHO/M	Almost negligible, its 10-¹³ MHO/M
Energy Band Gap	No energy gap exists	Its energy gap is 1 eV, which is greater than conductors but smaller than the insulators	Its energy gap is 5 eV, and it needs a huge amount of energy to push electrons
Resistance Power	Low	Normal	Very high
Resistivity Value	Less than 10-⁵Ω-M	Between 10-⁵Ω-M to 10-⁵Ω-M	More than 10-⁵Ω-M
Coefficient of Resistivity	Positive Coefficient of Resistivity	Negative Coefficient of Resistivity	Negative Coefficient of Resistivity
Number/s of valence electrons in outer shell	1 valence electron	4 valence electrons	8 valence electrons
Process of Formation	Formed by metallic bonding	Formed by covalent bonding	Formed by Ionic bonding
Behaviour in Absolute Zero point (0 Kelvin)	Act like a super-conductor	Act as an insulator	Act as an insulator

Conclusion

Conductors are an essential substance for electricity transmission. They have many real-life applications. On the other hand, while semiconductors have huge technology applications, insulators help reduce the risk of electrical fires and make the circuit safe to touch. Graphite is the only non-metal that can conduct electricity.Rubber is an excellent insulator.Rubber is also used in switchboards and electrical sheathing.Semiconductors are used in designing logic gates, digital circuits, and analogue circuits like oscillators and amplifiers.