Any materials that does not allow current to pass through it

Insulator

Any materials that allows current to pass through it

Conductor

the ability of the material to allow current to flow is known as CONDUCTIVITY

Conductivity in solids

The circuit is made up of a battery (a source of direct current), some connecting copper wires fitted with clips, and a light bulb to show when a current is flowing.

Metals (and graphite) conduct electricity because they have mobile free electrons in their structure that are able to flow through it.

Electrolysis

Electrolysis is the process of decomposing (breaking down) an ionic substance.

ELECTROLYTE is substances ( liquid or solution) that contain ionic compound.

Ion is free to move

Conductivity in liquids

If the compound is bonded covalently, then it will not conduct electricity as a liquid or as a solution.

Ionic compounds will conduct electricity if they are either molten or dissolved in water. Examples of these are molten lead bromide, sodium chloride solution and copper(ii) sulfate solution

Liquids that conduct electricity by movement of ions are called electrolytes. Liquids that do not conduct in this way are called non-electrolytes.

When electrolytes conduct electricity, chemical change takes place and the ionic compound is split up.

For example, lead bromide is changed to lead and bromine: PbBr2(l) → Pb(l) + Br2(g)

​Why covalent compound cannot conduct electricity?

​Why solid ionic compound does not conduct electricity?

In summary, the following substances are electrolytes:

◆ molten salts

◆ solutions of salts in water

◆ solutions of acids

◆ solutions of alkalis.