Final answer:
The Aufbau principle, Pauli exclusion principle, and Hund's rule are three fundamental rules that guide the filling of electron orbitals in an atom. The Aufbau principle states that electrons occupy the lowest-energy orbitals first, while the Pauli exclusion principle ensures that no two electrons in an atom can have the same set of four quantum numbers. Hund's rule states that electrons will first singly occupy different orbitals of the same energy before pairing up.
Step-by-step explanation:
The Aufbau principle, Pauli exclusion principle, and Hund's rule are three fundamental rules that guide the filling of electron orbitals in an atom.
- Aufbau principle: This principle states that electrons occupy the lowest-energy orbitals first. They fill the orbitals in a specific order, starting with the 1s orbital, followed by 2s, 2p, 3s, and so on. The orbitals within a given shell (like 2p) are filled in order of increasing energy.
- Pauli exclusion principle: According to this principle, no two electrons in an atom can have the same set of four quantum numbers, which describe the electron's energy, shape, orientation, and spin. This means that if two electrons are in the same orbital, they must have different spins.
- Hund's rule: Hund's rule states that when electrons occupy degenerate (same energy) orbitals, they will first singly occupy different orbitals of the same energy (spin up or spin down) before pairing up. This results in unpaired electrons in different orbitals within the same subshell, maximizing the atom's stability.
Overall, these three rules help determine the electron configuration of an atom, which affects its chemical properties and behavior.