Aufbau Principle

The Aufbau Principle is a guideline for determining the electron configuration of an atom. It states that electrons occupy the lowest energy levels first before filling higher ones. Imagine a building: you fill the lower floors (low energy levels) before moving to the upper floors (higher energy levels). This principle helps us understand how electrons are arranged around an atom's nucleus, influencing its chemical properties and behavior. For instance, in oxygen, electrons fill the 1s, then 2s, and finally the 2p orbitals, leading to its specific reactivity and bonding patterns.