What happens to atoms with completely filled valence bands?

Atoms with completely filled valence bands are chemically stable because their outermost electron shells are fully occupied. When an atom's valence band is complete, it generally reduces the likelihood of forming chemical bonds with other atoms. This stability arises from the fact that there are no available electrons to participate in bonding; thus, the atom is less reactive and tends to be inert.

For example, noble gases like helium and neon have full valence shells, making them largely unreactive. In contrast, atoms with incomplete valence bands often seek to gain, lose, or share electrons to achieve a full outer shell, which leads to chemical reactivity.

In summary, a completely filled valence band indicates that the atom is in a stable electronic configuration, leading to a state of low reactivity and a tendency to not form bonds easily.