eis3nheim

It would be helpful if you can tell us whether you are an studying electrical engineering, physics or chemistry and if you have heard of Fermi?

Iam studing electrical engineering, and this statement is about the semiconductors.

Do you know what the Pauli exclusion principle is?

No.

Would you explain it.

It's related to the Pauli exclusion principle. The electrons can't occupy the same state, so there must be an energy difference between them. That works if there is a band of energy states they can occupy, rather than one of a single value.

Would you explain it please

To understand this first you need the Pauli Exclusion Principle.

 

This states (for this purpose) thjat no two electrons can have the same set of quantum numbers.

 

 

Now the usual quantum solution that we use to describe an atom is for an 'isolated' atom.

That is it specifies a set of quantum numbers for an single atom in isolation.

 

But if we have two such atoms the set will be the same.

So what happens if we join them together?

 

Well each nucleus influences the other's bonding electons (that is what bonding means) and the electrons directly involved in the joining enter what are known as molecular orbitals with enough quantum numbers to hold them all.

 

Move on to a full crystal which is also called a periodic structure and you find 'super molecular orbitals' which can hold all the input electrons.

Obviously in order to obey the Pauli Principle the super molecular orbital must 'split' into many closely spaced (sub)orbitals to accomodate all its electrons.

 

Does this help?

But how that result in the expansion of the energy level ?