Electrons, when populating atomic orbitals, initially occupy the available orbitals possessing the least amount of energy. This principle dictates that electrons fill the 1s orbital before occupying the 2s orbital, and so forth. For example, consider the element carbon, which has six electrons. Two electrons will occupy the 1s orbital, followed by two electrons filling the 2s orbital, leaving the final two electrons to occupy the 2p orbitals.
Adherence to this filling order is crucial for understanding and predicting the electronic configuration of atoms and ions. It allows for accurate determination of an element’s chemical properties and its potential to form chemical bonds. Historically, this understanding emerged from spectroscopic studies and theoretical developments in quantum mechanics, which provided a framework for describing the behavior of electrons within atoms.
