How does the ionic radius of a nonmetal compare radius?

Question

Avery Adams · Accepted Answer

The ionic radius of a non-metal SHOULD be GREATER than the atomic radius........Why?

Because they typically originate from the left side of the Periodic Table, metals have a nuclear charge that is lower than that of non-metals, which originate from the right side. Metals are typically electron-rich materials with a tendency toward reducing chemistry. And thus metals, especially Group 1 and Group 2 metals, TEND to be reducing. It is very easy to form #Li^+#, and #Na^+#, and #Mg^(2+)# ions, i.e. alkali metal, and alkaline earth ions. Towards the right of the Periodic Table, nuclear charge has increased, and the incomplete valence shell SHIELDS the nuclear charge very ineffectively. The result is that as we go across a Period from left to right, the individual atoms become smaller, and ALSO, ionization energies become larger. This is a Periodic Trend with which you have to become very familiar. The result? When a non-metal forms an ion, it tends to do so by REDUCTION, i.e. addition of an electron to the valence shell. Both oxygen and fluorine form anions, #O^(2-)#, and #F^-#, with a complete valence shell. Because the electron adds to the shell, and there is not a compensating increase in nuclear charge, the atomic radii of ANIONS should be much greater than that of the parent atom. In any case, I would search your text for information on ionic versus atomic radius for elements, cations, and anions.

Natalie Anton · Answer

undefined The ionic radius of a nonmetal tends to be larger than its atomic radius due to the gain of electrons when forming an anion, resulting in increased electron-electron repulsion and expansion of the electron cloud.