The difference between Aufbau principle and pauli exclusion principle?

Answer 1

according to hund's rule ,electrons are distributed among the orbitals having equal energy [degenerate orbitals] in such a way that the number of unpaired electrons is maximum.In other words , if the number of electrons is less or equal to the orbitals of same energy then all these electrons will be unpaired.But when the number of electrons is more than the available orbitals , then first all the orbitals will be singly occupied and then pairing of electrons will start.Due to this interelectronic repulsion will be minimum when the electrons occupy separate orbitals and when number of unpaired electrons with same spin is greater than exchange energy will also be greater this stablizes the system.

While pauli's exclusion principle is that an orbital can accomodate not more than 2 electrons that too with opposite spins.

Answer 2

The Aufbau principle states that all electrons must begin at the lowest energy level. The electrons are more stable if they build up from the nucleus with the least energy than further from the nucleus with a higher energy. As each orbital is filled in the sublevels of the principle quantum numbers, or main energy levels, the electrons exist in an excited state rather than at ground state.

The Pauli Exclusion principle states that in each orbital, which can fit two electrons, no two electrons can have identical spins. A spin can be represented by a down arrow or an up arrow, being named similarly.

Hund's Rule is the third important principle which states that electrons singly occupy an orbital until that sublevel is filled. Only then do they double up. Think of what you do when you walk into a restaurant with three tables occupied by one person each. Do you sit at an empty table or with the other customers? Usually you would take a separate table until the restaurant, representing the sublevel, is full. Then, you move on to a different sublevel, or restaurant.

The order of sublevels goes from s, p, d ,f. The number of sublevels depends on the energy level. For example, if the principle quantum number is 2, then there are two sublevels, s and p.

With a little research (try typing the three names in to Wikipedia to get more details) and thought you can answer your own question. This is just designed as a starter. I think it is so obvious what the differences are once you have the definitions, which you can get on the computer in five seconds. That's what I did. Don't be lazy. I hope this helped you out.

Answer 3

The pauli exclusion principle (PEP) is a special case of the pauli principle.

The pauli principle states that if two ientical particles are swapped or exchanged the total wavefunction must not change (except for a possible change of sign). If the particles are bosons the wavefunction remains the same, if fermions the wavefunction changes sign.

The pep does not apply to bosons, only fermions. The pep prevents two identical fermions entering the same spatial wavefunction i.e. must not have the same values of n, l, ml and ms quantum numbers.