The compression of an atom is not a straightforward concept because the size of an atom is primarily determined by the electron cloud surrounding the nucleus. The electron cloud is governed by quantum mechanics, and the electrons occupy specific energy levels or orbitals. These orbitals have a certain spatial extent associated with them.
While it is possible to bring atoms closer together under extreme conditions, such as high pressures or temperatures, there are limits to how much they can be compressed. When atoms are compressed, their electron clouds start to overlap, resulting in repulsive forces between the electrons. These repulsive forces prevent the atoms from being compressed beyond a certain point.
Furthermore, at extremely high pressures, the behavior of matter can change significantly. For example, certain elements can undergo a phase transition and transform into a denser state, such as a solid becoming a liquid or a gas becoming a solid. In such cases, the atoms or molecules are still present, but their arrangement and properties may be different.
It's also worth noting that when we talk about compressing atoms, we usually refer to compressing a bulk material made up of a large number of atoms. The compression of an individual isolated atom doesn't have a practical meaning in most contexts.
In summary, while there are limits to how much atoms can be compressed due to repulsive forces between electrons, extreme conditions can lead to changes in the arrangement and behavior of matter, resulting in denser states.