Question

Difference between aufbau and pauli's exclusion principles

Answer 1

Answer:

The Aufbau Principle:-

• states that lower energy orbitals fill before higher energy orbitals.
• For example, the orbitals in the n= 1 energy level will fill up before the orbitals in the n=2 energy level.
• According to this principle, the electrons will first occupy the orbitals that have the lowest energy.
• This means that the electrons enter first orbital and then enter the orbitals which have higher energy but only when the lower- energy orbitals are completely filled.
• The order in which the electrons should be filled is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…..
• The order of the increasing energy of the orbitals can also be calculated using (n+l) rule.
• The sum of the values of the principal quantum numbers (n) and azimuthal quantum number (l) is used to decide the energy level of an orbital.
• The lower value of the sum of (n+l) implies that the energy of the orbital is low.
• If the value of n+l for two orbitals is equal then the orbital with a lower value of n will have a lower energy level.

The pauli's exclusion principal:-

• The principal states that no two electrons can be identified by the same set of quantum numbers.
• This is actually why we have the spin quantum number, ms to ensure that two electrons within the same orbital have unique sets of quantum numbers.
• You may also hear this in the form that the two electrons in an orbital must have opposite spins, which essentially means the same thing.
• According to this principle, an orbital can have maximum two electrons and these must have opposite spins.
• In other words, no two electrons in an atom can have all the four quantum numbers exactly the same.
• As we know that fourth quantum number is m, 1/2 is spin up and -1/2 is spin down and hence if the first three quantum numbers are same for two electrons then the electrons must have opposite spins in an orbital.

Explanation:

hope it's help you!!!

Answer 2

The aufbau principle, from the German Aufbauprinzip, also called the aufbau rule, states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels.

For example, the 1s subshell is filled before the 2s subshell is occupied