Which of the following best describes the molecular geometry and approximate bond angle of the nitrate ion (NO_3^-)?

• A. Trigonal planar, 120°
• B. Bent, 104.5°
• C. Linear, 180°
• D. Tetrahedral, 109.5°

Answer: (A)

Verified step by step guidance

1. Identify the central atom in the nitrate ion (NO_3^-), which is nitrogen (N).
2. Determine the number of regions of electron density around the central nitrogen atom. This includes bonding pairs and lone pairs. For NO_3^-, nitrogen is bonded to three oxygen atoms and has no lone pairs.
3. Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to predict the molecular geometry. With three bonding pairs and no lone pairs, the electron pairs will arrange themselves to minimize repulsion, resulting in a trigonal planar shape.
4. Recall that in a trigonal planar geometry, the bond angles between the atoms are approximately 120° because the three groups are evenly spaced in a plane.
5. Compare the given options and select the one that matches the trigonal planar geometry and 120° bond angle, which is the correct description of the nitrate ion.