What is an atom considered when it is in a state of equilibrium?

An atom is considered neutral when it is in a state of equilibrium because neutral atoms have an equal number of protons and electrons. This balance results in no net electrical charge on the atom, allowing it to be stable and unreactive under normal conditions. In a neutral state, the forces acting on the atom are balanced, meaning that it is not gaining or losing electrons, which keeps the atom in a stable configuration.

Other states, such as ionized (where the atom has lost or gained electrons and holds a charge), reactive (indicating a tendency to engage in chemical reactions due to an imbalance of electrons), or excited (referring to electrons being in higher energy states than normal) are all conditions that deviate from equilibrium. Therefore, equilibrium in the context of atomic structure specifically describes the balance of charges, leading to a neutral atom.