Common ionic radius examples for main group elements and transition metals

📚 Quick Study Guide

• ⚛️ Ionic radius refers to the radius of an ion in an ionic crystal.
• ➕ Cations (positive ions) are smaller than their parent atoms because they lose electrons, increasing the effective nuclear charge.
• ➖ Anions (negative ions) are larger than their parent atoms because they gain electrons, decreasing the effective nuclear charge.
• 📈 Ionic radii generally increase down a group in the periodic table due to the addition of electron shells.
• ➡️ For isoelectronic species (atoms/ions with the same number of electrons), the ion with the larger nuclear charge will have a smaller radius.
• 📏 Trends for transition metals are more complex due to varying oxidation states and the effects of d-electrons.
• 🧪 Common ions: $Na^+, Mg^{2+}, Al^{3+}, Cl^-, O^{2-}, S^{2-}$ for main group elements; $Fe^{2+}, Fe^{3+}, Cu^+, Cu^{2+}, Zn^{2+}$ for transition metals.

Practice Quiz

1. Which of the following statements is true regarding ionic radii?
   1. A) Cations are larger than their parent atoms.
   2. B) Anions are smaller than their parent atoms.
   3. C) Cations are smaller than their parent atoms.
   4. D) Anions and cations are always the same size.
2. Which of the following ions is the smallest?
   1. A) $O^{2-}$
   2. B) $F^-$
   3. C) $Na^+$
   4. D) $Mg^{2+}$
3. Which of the following elements, when ionized to achieve a noble gas electron configuration, will form the largest ion?
   1. A) Na
   2. B) Mg
   3. C) O
   4. D) F
4. Which of the following pairs represents an isoelectronic series?
   1. A) $K^+, Ca^{2+}, Ar, Cl^-$
   2. B) $Na^+, Mg^+, Al^+$
   3. C) $O, S, Se$
   4. D) $Li, Na, K$
5. Which of the following transition metal ions is likely to have the smallest ionic radius?
   1. A) $Fe^{2+}$
   2. B) $Fe^{3+}$
   3. C) $Cu^+$
   4. D) $Zn^{2+}$
6. As you move down Group 1 (alkali metals), how does the ionic radius of the +1 ion change?
   1. A) Decreases
   2. B) Increases
   3. C) Stays the same
   4. D) Varies unpredictably
7. Which of the following has the smallest ionic radius?
   1. A) $Al^{3+}$
   2. B) $Na^+$
   3. C) $K^+$
   4. D) $Cs^+$