Gases are generally considered insulators because they are poor conductors of electricity. This is because their electrons are too far apart to be able to disperse current. With this said, noble gases are the exception when used at low pressure and high voltage.
These gases consist of neon, radon, argon, xenon, helium, and krypton. Types of elements that are considered to be good conductors of electricity are generally metals like aluminum, copper, gold, and silver. Metals conduct electricity well because they are solid and can transfer current.
An insulator is a substance or technique that blocks the exchange of either heat or electricity. Insulators or non-conductors are used to protect us from the dangerous effects of electricity flowing through the conductors. Gases do not conduct heat as well as liquids and are therefore good insulators. Gases consist of widely spread out particles, and it takes contact to conduct heat.
All gases are insulators. They are insulators if they are not ionized and there are no free charged particles there that can carry electric current. Electronegative gases are good insulators since the ions rapidly combine with the ions produced in the spark.
No! It is not necessary that all gases are insulators. Although, it’s all true that most gases are bad conductors of electricity and only a small number of gases can conduct electricity.
Gases conduct electricity only when we subject them to lower pressure and higher voltage. Gases are very poor conductors of electricity at normal atmospheric pressure due to the deficiency of free electrons to carry current across. But, we can produce free electrons in the gaseous state by applying the above-mentioned ways.
Low Pressure increases the interatomic distances and the applied higher voltage excites the particles which lead to more interatomic collisions increasing the K.E. of the particles which ionizes the atoms.