Final answer:
The ground state electron configuration of an atom must obey the Pauli Exclusion Principle, Hund's Rule, and the Aufbau Principle, which dictate the unique positioning and energy levels of electrons within an atom.
Step-by-step explanation:
The ground state electron configuration of an atom must obey all of the following rules: a) Pauli Exclusion Principle, b) Hund's Rule, and c) Aufbau Principle.
Pauli Exclusion Principle
Proposed by Austrian physicist Wolfgang Pauli in 1925, the principle states that no two electrons can have the same set of four quantum numbers, meaning no two electrons can be in the same quantum state. This principle ensures each electron has a unique 'address' within an atom.
Hund's Rule
This rule indicates that when electrons occupy orbitals of equal energy (degenerate orbitals), they must first half-fill each orbital with parallel spins before they can pair up.
Aufbau Principle
Electrons fill the lowest energy orbitals first, following a defined sequence from the 1s orbital upwards, as per the ordering dictated by quantum mechanics and the periodic table. It involves 'building up' the electronic structure of an atom by adding protons to the nucleus and electrons to the corresponding subshells.