Multiple Choice
Which of the following elements forms an ion that is smaller in radius than a Ca^{2+} ion?
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10. Periodic Properties of the Elements
Periodic Trend: Ionic Radius
Multiple Choice
Which of the following statements correctly describes the periodic trend of ionic radius?
A
Ionic radius generally increases across a period from left to right.
B
Ionic radius generally increases down a group.
C
Anions are always smaller than their parent atoms.
D
Cations are always larger than their parent atoms.
Verified step by step guidance1
Understand that ionic radius refers to the size of an ion, which can be either a cation (positively charged) or an anion (negatively charged).
Recall the general periodic trends: as you move down a group in the periodic table, atoms gain more electron shells, which increases the size of the ion or atom.
Recognize that moving across a period from left to right, the number of protons increases, pulling electrons closer and generally decreasing atomic and ionic size, so ionic radius usually decreases across a period.
Know that anions (negatively charged ions) are larger than their parent atoms because they gain electrons, increasing electron-electron repulsion and expanding the electron cloud.
Know that cations (positively charged ions) are smaller than their parent atoms because they lose electrons, reducing electron-electron repulsion and allowing the remaining electrons to be pulled closer to the nucleus.
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