What makes up most of the volume of an atom?

The volume of an atom is primarily made up of the electron cloud. This cloud consists of electrons that are arranged in various energy levels around the nucleus. The electrons are not located in fixed paths but rather in probabilistic regions known as orbitals, creating a "cloud-like" area where the likelihood of finding an electron is highest.

While the nucleus, which contains protons and neutrons, is significantly denser and contains most of the atom's mass, it occupies only a very small part of the overall atomic volume. In contrast, the electron cloud extends much further out and encompasses a much larger volume, influencing the atom's size and shape. Therefore, it's this distribution of electrons in the cloud that defines the atomic volume, making the electron cloud the critical factor in understanding the spatial characteristics of an atom.