AP Chemistry Questions on Molecular Polarity

📚 Quick Study Guide

• ⚛️ Molecular polarity depends on both the polarity of individual bonds and the molecular geometry.
• ➡️ A bond is polar if there's a significant difference in electronegativity between the bonded atoms (typically > 0.4).
• 📐 Molecular geometry (linear, trigonal planar, tetrahedral, etc.) determines if bond dipoles cancel out.
• ➕ If bond dipoles cancel, the molecule is nonpolar; if they don't, the molecule is polar.
• 💧 Polar molecules have a net dipole moment.
• ⚡️ Key electronegativity trends: Increases across a period, decreases down a group.
• 📝 Use VSEPR theory to predict molecular geometry.

🧪 Practice Quiz

1. Which of the following molecules is polar?
   1. $CO_2$
   2. $BF_3$
   3. $CCl_4$
   4. $H_2O$
2. Which of the following molecules has polar bonds but is nonpolar overall?
   1. $NH_3$
   2. $H_2S$
   3. $CF_4$
   4. $HF$
3. Which of the following bonds is the most polar?
   1. C-H
   2. O-H
   3. N-H
   4. F-H
4. Which of the following molecules is nonpolar due to its symmetrical shape?
   1. $CHCl_3$
   2. $SO_2$
   3. $BeCl_2$
   4. $H_2O$
5. Which of the following statements about polar molecules is correct?
   1. They always have linear geometry.
   2. They have a symmetrical distribution of charge.
   3. They dissolve well in nonpolar solvents.
   4. They have a net dipole moment.
6. Which of the following molecules exhibits dipole-dipole interactions?
   1. $CH_4$
   2. $CO_2$
   3. $SO_2$
   4. $C_2H_6$
7. Which of the following molecules is predicted to have a bent molecular geometry and be polar?
   1. $CS_2$
   2. $N_2$
   3. $OF_2$
   4. $BeH_2$