What is the molecular geometry around a central atom with three bonded atoms and no lone pairs?

What is the molecular geometry around a central atom with three bonded atoms and no lone pairs?

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

Answer: (B)

VSEPR theory shows that the shape is determined by the number of electron domains around the central atom. With three bonded atoms and no lone pairs, there are three regions of electron density. These three regions arrange themselves as far apart as possible in a single plane, giving bond angles of about 120 degrees. The resulting geometry is trigonal planar. This differs from tetrahedral geometry, which needs four electron regions; bent and pyramidal shapes arise when lone pairs are present and alter the arrangement. An example of trigonal planar is BH3.

VSEPR theory shows that the shape is determined by the number of electron domains around the central atom. With three bonded atoms and no lone pairs, there are three regions of electron density. These three regions arrange themselves as far apart as possible in a single plane, giving bond angles of about 120 degrees. The resulting geometry is trigonal planar. This differs from tetrahedral geometry, which needs four electron regions; bent and pyramidal shapes arise when lone pairs are present and alter the arrangement. An example of trigonal planar is BH3.