* Electron configuration: Sodium has one valence electron in its outermost shell. When it loses this electron, it achieves a stable electron configuration like the noble gas Neon.
* Effective nuclear charge: The loss of an electron reduces the electron-electron repulsion within the atom. This allows the remaining electrons to be pulled closer to the nucleus by the positive charge of the protons.
* Ionic radius: The result is a smaller ionic radius for the sodium ion compared to the neutral sodium atom.
In summary: The loss of an electron leads to a stronger attraction between the nucleus and the remaining electrons, resulting in a smaller ionic size.
