The electron configuration with the greatest stability is that of a noble gas, characterized by a completely filled valence shell. This full outer shell typically contains eight electrons (an octet) in the s and p sublevels, except for helium, which is stable with two electrons filling its 1s sublevel (a duet). This full valence shell configuration is energetically favorable and makes the atom very stable and largely unreactive
. In addition to full shells, certain subshell configurations also confer extra stability:
- Full subshells , such as a completely filled d subshell (d^10), provide significant stability. For example, zinc’s electron configuration ends in 4s^2 3d^10, which is quite stable
- Half-filled subshells (e.g., p^3 or d^5), where each orbital in a subshell has one electron, also offer enhanced stability due to electron exchange energy and symmetry. Nitrogen (2p^3) and manganese (3d^5) are examples of this
However, the highest stability is achieved with a full valence shell , as seen in noble gases like neon (1s^2 2s^2 2p^6) or argon (1s^2 2s^2 2p^6 3s^2 3p^6), which have paired electrons in all their outer orbitals and are chemically inert
. In summary:
- The most stable electron configuration is a full valence shell , typically the noble gas configuration.
- Secondary stability arises from full subshells (especially d^10) and half-filled subshells (like p^3 or d^5).
- Atoms tend to gain, lose, or share electrons to achieve these stable configurations
