Multiple Choice
What is the molecular geometry of a molecule with 5 outer atoms and 1 lone pair on the central atom?
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12. Molecular Shapes & Valence Bond Theory
Molecular Geometry
Multiple Choice
What is the molecular geometry of HCN (hydrogen cyanide)?
A
Bent
B
Angular
C
Trigonal pyramidal
D
Linear
Verified step by step guidance1
Identify the central atom in the molecule HCN. In this case, carbon (C) is the central atom bonded to hydrogen (H) and nitrogen (N).
Determine the number of regions of electron density (bonding and lone pairs) around the central atom. Carbon forms two sigma bonds: one with hydrogen and one with nitrogen, and has no lone pairs.
Use the VSEPR (Valence Shell Electron Pair Repulsion) theory to predict the molecular geometry. With two regions of electron density and no lone pairs, the electron pairs will arrange themselves to be as far apart as possible.
Recognize that two regions of electron density around the central atom result in a linear geometry, with a bond angle of approximately 180 degrees.
Conclude that the molecular geometry of HCN is linear, not bent, angular, or trigonal pyramidal.
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