Which molecular geometry is expected for a molecule with the formula AX_2, where the central atom has two regions of high electron density (RHEDs) and no lone pairs?

• A. Tetrahedral
• B. Linear
• C. Trigonal planar
• D. Bent

Answer: (B)

Verified step by step guidance

1. Identify the central atom and the number of regions of high electron density (RHEDs) around it. In this case, the central atom has two RHEDs and no lone pairs.
2. Recall that the molecular geometry depends on the number of RHEDs and the presence of lone pairs. For two RHEDs with no lone pairs, the electron pairs will arrange themselves to minimize repulsion by being as far apart as possible.
3. Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to predict the shape. Two bonding pairs with no lone pairs will arrange linearly to maximize the distance between them.
4. Write the general formula for the molecular geometry of AX_2 with two bonding pairs and no lone pairs, which corresponds to a linear shape with a bond angle of 180°.
5. Conclude that the expected molecular geometry for AX_2 with two RHEDs and no lone pairs is linear.