Question

Difference between aufbau principle ,pauli's exclusion and hund's principles

Answer 1

Aufbau principle states that electron will fill the lower energy levels before moving to higher energy levels.

Pauli's exclusion principle states that two electrons cannot exist at the same location and therefore the electrons in the orbitals have opposite spins.

Helium has a atomic number of 2 means have 2 electrons that have opposite spins.

According to Hund's rule, electrons will fall into empty orbitals of same energy before electrons begin to pair up into the the same orbital.

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.....