Question

Question: Predict the geometry around each highlighted atom

a.

b.

c.

d.

e.

Short answer

Answer

a. Tetrahedral

b. Bent

c. Trigonal planar

d. Trigonal planar

e. Trigonal pyramidal

Step-by-step solution

Step-by-Step SolutionStep 1: Represent the expanded form of structure

Write all the groups and lone pairs of electrons attached to the shaded atoms in expanded form. Hence, check the octet of the shaded atom.

Predict the geometry

Count the number of surrounding atoms and groups around each atom and predict geometry as per hybridization.

If there are more than one lone pair of electrons, the high repulsions among the lone pairs of electrons due to which the geometry will be different.

 Step 3: Predict the geometry of the given compounds

a. The shaded carbon atom has four atoms around it. Hence, it has a tetrahedral geometry.

Structure of a

b. The shaded nitrogen atom has two lone pairs of electrons and two methyl groups, i.e., . The geometry for four groups attached to an atom is tetrahedral.

However, since the nitrogen atom is surrounded by two lone pairs of electrons on one side, these pairs create high repulsions.

So, the methyl groups get closer to each other, and the molecule acquires the bent geometry rather than the expected tetrahedral for the four groups attached

Structure of b

c. The shaded carbon is tetravalent, having one double bond and three groups attached to it. So, the geometry of the shaded carbon is trigonal planar.

Structure of c

d. The shaded carbon atom is attached to three groups, so it has a trigonal planar geometry.

Structure of d

e. The shaded nitrogen atom has a lone pair of electrons and three groups attached to it. The geometry for the four attached groups is tetrahedral.

However, since the nitrogen atom has one lone pair and three bond pairs, the molecule acquires a trigonal pyramidal geometry.

Structure of e