* Electron Configuration: A sodium atom has 11 electrons, with its outermost electron being in the 3s orbital. When sodium loses this outermost electron to become a positively charged ion (Na+), it loses its entire third energy level.
* Effective Nuclear Charge: The positive charge of the nucleus attracts the electrons. When a sodium atom loses an electron, the number of protons in the nucleus remains the same, but there are now fewer electrons. This means the remaining electrons are pulled in more strongly by the nucleus, resulting in a smaller ionic radius.
* Shielding: The inner electrons shield the outer electrons from the full attraction of the nucleus. With the loss of the outermost electron, the remaining electrons experience less shielding, increasing the attraction of the nucleus and causing a further reduction in size.
In summary: The loss of an electron in sodium results in a smaller ionic radius due to the increased effective nuclear charge and reduced electron-electron repulsion.
