Pregunta 3 · Química I URV 2019

Arrange the following species in order of increasing radius:

Solución: $\mathrm{Y}^{3+} < \mathrm{Sr}^{2+} < \mathrm{Rb}^+ < \mathrm{Kr} < \mathrm{Br}^- < \mathrm{Se}^{2-}$

Comment on the principles involved in doing so:

Solución: All species are isoelectronic (36 electrons). In an isoelectronic series, shielding is constant, so effective nuclear charge (Zeff) increases with atomic number Z. Greater nuclear charge pulls electrons closer, making cations smaller and anions larger.