Why do insulators not conduct electricity?

Answer 1

Simple Answer:
The fundamental difference between a conductor and an insulator is that some electrons of the atoms of a conductor are not stuck to specific atoms but are free to move throughout the material. For insulators, the electrons are tightly bound to the specific atoms or in the chemical bonds between atoms. A relatively small force created by the electric field due to an applied voltage produces a tremendous movement of the nearly free electrons in a metal and almost no response at all from tightly bound electrons in an insulator.

Longer Answer:
For a material to carry electricity, it must contain charge carriers that move.
In metals, the outermost electrons of the atoms are not localized on the atoms, but extend far out into the material and are often termed delocalized. This is a way of saying that electrons in metals are essentially free to move throughout the material. As a consequence, little or no energy is required to transport electrons through a metal. Metals are thus good conductors of electricity.

Materials that are insulators have electrons that are localized on specific atoms or localized in particular chemical bonds that join atoms. To move an electron from one atom to the next requires some energy to initially dislodge it. On the atomic scale, the electric field to dislodge an electron from one atom and move it to a nearby atom is typically very large for materials that are not metals. As a result, most materials are insulators.

Finally, it is worth pointing out that ionic liquids, like salt water, conduct electricity not as moving electrons but as a consequence of the movement of charged atoms, e.g. Na+ and Cl-. Conversely, a solution of sugar does not ionize and the molecules are not charged, so conductivity is nearly zero.

Caveat: For the expert, the ultimate quantitative answer to this question requires discussing quantum theory of electrons in solids and band structure and impurities and defects and lattice vibrations.

Answer 2

Conductor atoms (usually metals) contain free electrons. That is their valence electrons are free to move throught the whole substance. So, when an electric current is applied to the substance, they carry the charges through out the material but insulators do not contain free electrons and so no particle can carry charges through the sustance. This make insulators not to conduct electricity.

Answer 3

Because an insulator is defined as a substance that electricity doesn't flow through, it is tougher for the material to conduct electricity. Examples of insulators include cloth, paper, plastic, and wood.

Answer 4

Insulators do not conduct electricity because they have very few free electrons available to carry an electric current. The electrons in insulators are tightly bound to their atoms, making it difficult for them to move through the material and thus hindering the flow of electricity.