Which molecule is bent due to two lone pairs on the central atom?

Which molecule is bent due to two lone pairs on the central atom?

• A. Methane
• B. Water
• C. Ammonia
• D. Carbon dioxide

Answer: (B)

Think of how pairs of electrons around the central atom arrange themselves to minimize repulsion in the VSEPR model. When there are two lone pairs on the central atom, they push the bonding pairs apart more strongly, creating a bent shape rather than a straight or pyramidal one. In water, the oxygen atom has two lone pairs and forms two O–H bonds. Those lone pairs occupy significant space and repulsively bend the molecule, giving the H–O–H angle of about 104.5 degrees. Methane has no lone pairs on carbon, so it is tetrahedral; ammonia has one lone pair, giving a trigonal pyramidal shape; carbon dioxide has no lone pairs on carbon and is linear. Thus water is the bent molecule due to two lone pairs on the central atom.

Think of how pairs of electrons around the central atom arrange themselves to minimize repulsion in the VSEPR model. When there are two lone pairs on the central atom, they push the bonding pairs apart more strongly, creating a bent shape rather than a straight or pyramidal one. In water, the oxygen atom has two lone pairs and forms two O–H bonds. Those lone pairs occupy significant space and repulsively bend the molecule, giving the H–O–H angle of about 104.5 degrees. Methane has no lone pairs on carbon, so it is tetrahedral; ammonia has one lone pair, giving a trigonal pyramidal shape; carbon dioxide has no lone pairs on carbon and is linear. Thus water is the bent molecule due to two lone pairs on the central atom.