Question

for the molecule below, choose the image that accurately does all of the following • shows the pair of electrons shared between atoms • shows the electrons closest to the more electronegative atom or in the middle of the bond if the atoms are roughly equally electronegative (<0.5 difference) • correctly labels partial charges if there are any • places and asterisk next to any polar covalent bonds • indicates whether the molecule is polar or nonpolar

Explanation:

To solve this, we analyze the molecule \( \text{CH}_3\text{OH} \) (methanol):

Step 1: Analyze Bonds and Electronegativity

• \( \text{C-H} \): Electronegativity difference \( < 0.5 \) (nonpolar covalent, electrons shared equally).
• \( \text{C-O} \) and \( \text{O-H} \): Electronegativity difference \( > 0.5 \) (polar covalent, electrons pulled toward \( \text{O} \), so \( \text{O} \) has \( \delta^- \), \( \text{C/H} \) have \( \delta^+ \)).

Step 2: Check Partial Charges and Polarity

• \( \text{C-H} \) bonds: No partial charges (or very small, \( \delta^+ \) on \( \text{H} \), \( \delta^- \) on \( \text{C} \) but minimal).
• \( \text{C-O} \) and \( \text{O-H} \): \( \text{O} \) is \( \delta^- \), \( \text{C/H} \) are \( \delta^+ \).
• Molecule polarity: Methanol has a polar \( \text{O-H} \) bond and a polar \( \text{C-O} \) bond, with an overall polar molecular geometry (due to the bent \( \text{O-H} \) and tetrahedral \( \text{C} \), but net dipole exists).

Analyzing the Options:

• First Option (with \( \delta^+ \) on \( \text{C} \), \( \delta^- \) on \( \text{O} \), and labeled "Polar Molecule"):
• Shows shared electron pairs (dots for bonds).
• Electrons near \( \text{O} \) (more electronegative) in \( \text{C-O} \) and \( \text{O-H} \); equally shared in \( \text{C-H} \).
• Partial charges: \( \delta^+ \) on \( \text{C} \), \( \delta^- \) on \( \text{O} \) (correct for polar bonds).
• Indicates "Polar Molecule" (correct, as methanol is polar).

Answer:

The first option (with \( \boldsymbol{\delta^+} \) on \( \boldsymbol{\text{C}} \), \( \boldsymbol{\delta^-} \) on \( \boldsymbol{\text{O}} \), and labeled "Polar Molecule") is correct.