Electrical properties Chemistry Notes
On the basis of conductivity, solids can be classified into three classes:
→ Conductors : The solids which can conduct electricity, are called conductors. The range of conductivity is in between 104 to 107 ohm-1 m-1
Conductors are of two types
- Metallic conductors
- Electrolytic conductors
→ The electrical conductivity in metallic solids is due to the movement of electrons. Metals conduct electricity in both solid as well as in fused state. The conductivity of metals depend on the number of valence electrons per atom.
→ The conductivity of metallic conductors decreases with increase in temperature. When electric current flows through a metal, no chemical reaction takes place. Electrolytic conductors conduct electricity in very less amount in solid state. Electrolytes conduct electricity in fused state and in their aqueous solutions. The electrolytic conductivity is due to movement of ions.
→ Insulators : The solids which do not conduct electricity are called insulators. Their conductivity is very less and lies in between range of 10-20 to 10-10 ohm-1 m-1
Examples – Sulphur, phosphorus, wood, plastic, rubber etc.
→ Semiconductors: The solids whose conductivity lies in between conductors and insulators are called semi conductors. Their conductivity is due to impurities and lattice imperfections and increases with increase in temperature.