Question

Which element is the best insulator?

Answer 1

Hint: The best insulators belong to the group of elements which have completely filled valence shells and are highly stable. They don’t even react with other elements due to their stability.

Complete answer:
Insulators are the materials which prevent the flow of electrons and in turn, they prevent the passage of electricity. Though a perfect insulator does not exist, the elements which allow the minimum passage of electric charge can be considered to be the best insulators.
Also, remember that all insulators may become conductive when a sufficient amount of high voltage current is applied which tears the electrons away from the atoms. We can say that this voltage is the breakdown voltage of an insulator.
Insulators are often used in electric appliances and electric wires to separate the electric conductors from the surrounding. This makes the electric appliances safe and also prevents us from getting electric shocks.
Metals are generally good conductors of electricity while non-metals are generally poor conductor electricity. There is an exception though which is graphite. Despite being non-metal, it can conduct good electricity due to the presence of free electrons in it.
The elements of group 18 of the periodic table are considered to be the best insulators. This is because they have completely filled the valence shell and they will not allow the electrons to move freely due to their high nuclear charge. Thus, they are highly stable.
There are also some other good examples of insulators such as silicon and sulphur. Diamond, which is entirely made up of carbon is also a good insulator since it doesn’t have any free electrons to conduct electricity. Some other compounds which are insulators are glass, rubber, oil, pure water etc.
Hence the best insulators are found in group 18 of the periodic table.

Note:
The choice of an insulator in an electrical appliance should be done carefully. We have to make sure that the breakdown voltage of the insulator must be greater than the voltage to be applied in the appliance. Or else, the insulator won’t be effective.