What principle states that electrons occupy the lowest energy level first?

The principle that states electrons occupy the lowest energy level first is known as the Aufbau Principle. This principle plays a crucial role in determining the electron configuration of atoms. According to the Aufbau Principle, electrons will fill atomic orbitals starting from the lowest available energy levels before moving to higher energy levels. This filling order is essential for understanding how atoms bond and react with one another, as the arrangement of electrons in various energy levels influences an element's chemical properties.

In the context of the Aufbau Principle, it is essential to recognize that each type of orbital has a specific energy associated with it, and electrons will seek to minimize their energy by occupying the lowest available orbitals. This foundational concept in quantum chemistry ultimately leads to the systematic arrangement of elements in the periodic table, directly influencing their behavior in chemical reactions.

Other principles mentioned, such as the Pauli Exclusion Principle and Hund’s Rule, address different aspects of electron configuration. The Pauli Exclusion Principle states that no two electrons can have the same set of four quantum numbers, which implies that an orbital can hold a maximum of two electrons with opposite spins. Hund’s Rule explains how electrons will fill degenerate orbitals (orbitals of the same energy) singly before pairing up. Quantum Theory encompasses a broader