The a property of materials C Si Ge depends upon the energy gap between their conduction and valence bands
Answers
Conductivity of the elements
Explanation:
Bands are formed by the closely spaced orbitals.
There are two types of bands:
1. Valance bands
2. Conduction bands
Valance band is a group of orbitals which contain electrons in the shell whereas conduction band is a group of empty orbitals of the shells that do not contain any electron due to their configuration making the orbitals of higher energy levels.
When the electrons pass from valance band to the conduction band these solids conduct electricity with flow of charges in the form of electrons.
In Conductors this energy gap is extended and the valance band and the conduction band overlap each other. This makes it easy for the electricity to pass through them.
In semi-conductors there is a slight gap between the conduction band and the valance band. This band gap is less than or equal to 1.4 eV. The electrons from valance shell takes a little energy to excite from valance band to the conduction band.
In insulators the energy gap is considerably large and the electrons of the valance band cannot be excited to the conduction band before the melting or the dissociation of the solid. Which means that under the practically ambient condition it cannot conduct electricity.
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TOPIC: band theory of solids
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