In which of the following atoms is the ionic radius larger than the atomic radius? [11 Na, 12Mg,13AI,17CI]

An atom becomes an ion by either gaining or losing electrons. When an atom gains an electron, it forms a negative ion (anion) which is larger than its corresponding neutral atom because the added electron increases the electron-electron repulsion and pushes the other electrons further away from the nucleus. Conversely, when an atom loses an electron, it forms a positive ion (cation) which is smaller than its corresponding neutral atom because the lost electron reduces the electron-electron repulsion and the remaining electrons are pulled closer to the nucleus. From the given options, only Chlorine (Cl) gains an electron to form a chloride ion (Cl⁻) which is larger than its atomic radius. The other elements (Na, Mg, and Al) lose electrons to form cations which are smaller than their atomic radii. Therefore, the correct answer is Chlorine (Cl).