Energy states refer to the specific levels of energy that particles, such as electrons, can occupy within an atom or molecule. These states are quantized, meaning that particles can only exist in certain energy levels and not in between. When energy is added to a particle, it can move to a higher energy state, while releasing energy can cause it to drop to a lower state. In the context of quantum mechanics, energy states play a crucial role in understanding how atoms interact and bond with one another. The arrangement of electrons in different energy states determines the chemical properties of elements and compounds, influencing reactions and the formation of molecules.