Final Answer:
Cations have smaller radii than their neutral atoms, and anions have larger radii than their neutral atoms.
Step-by-step explanation:
When considering the atomic structure and the formation of ions, it's essential to comprehend the changes that occur within the electron configuration. Cations are formed when atoms lose electrons, usually due to elements aiming to achieve a more stable electron configuration similar to the nearest noble gas. As an atom loses electrons to become a cation, the number of negatively charged electrons decreases while the positively charged protons remain constant in the nucleus. This reduction in the electron cloud's size results in a tighter, more contracted atomic structure, effectively reducing the atomic radius of the cation compared to its neutral state. This phenomenon occurs due to the increased attraction between the fewer electrons and the constant number of protons, drawing the remaining electrons closer to the nucleus.
On the contrary, anions form when atoms gain electrons, leading to an increase in the number of negatively charged electrons in the electron cloud. This addition of extra electrons causes greater electron-electron repulsion, pushing the electrons farther away from the nucleus. Consequently, the electron cloud expands, leading to an increase in the atomic radius of the resulting anion compared to its neutral atom. The added electrons introduce a greater level of electron-electron repulsion, which counteracts the pull of the protons in the nucleus, thereby enlarging the overall size of the anion.
Understanding these changes in atomic radii concerning cations and anions is crucial in comprehending the behavior of elements in chemical reactions and bonding. The variations in size directly impact how ions interact and form compounds, influencing their stability and reactivity. This fundamental concept in chemistry elucidates how alterations in electron configurations during ion formation significantly affect the size and properties of the resulting ions compared to their neutral atomic counterparts.