Answer: Shapes and Polarity of Polyatomic Molecules

Problem 41E

Shapes and Polarity of Polyatomic Molecules (Section)

(a) Consider the AF3 molecules in Exercise Which of these will have a nonzero dipole

moment? (b) Which of the AF4 molecules in Exercise will have a zero dipole moment?

The figure that follows shows ball-and-stick drawings of three possible shapes of an

AF3 molecule. (a) For each shape, give the electron-domain geometry on which the

molecular geometry is based., (b) For each shape, how many nonbonding electron

domains are there on atom A? (c) Which of the following elements will lead to an AF3

molecule with the shape in (ii): Li, B, N, AI, P, Cl? (d) Name an element A that is expected

to lead to the AF3 structure shown in (iii). Explain your reasoning.

The figure that follows contains ball-and-stick drawings of three possible shapes of an

AF4 molecule. (a) For each shape, give the electron-domain geometry on which the

molecular geometry is based., (b) For each shape, how many nonbonding electron

domains are there on atom A? (c) Which of the following elements will lead to an AF4

molecule with the shape in (iii): Be, C, S, Se, Si, Xe?

(d) Name an element A that is expected to lead to the AF4 structure shown in (i).

                                                             Step by Step Solution

Step 1 of 4

(a)

(i)

It is a nonpolar molecule with zero dipole moment. It is trigonal planar geometry. The vector

the addition of three individual A-F bonds is zero. In other words, the individual bond dipoles

cancel each other. An example is boron trifluoride .

(ii)

It is a polar molecule with nonzero dipole moment. It is pyramidal geometry. The vector addition

of three individual A-F bonds is nonzero. In other words, the individual bond dipoles do not

cancel each other. An example is ammonia .

(iii)

 It is a polar molecule with nonzero dipole moment. It is T-shaped geometry. The vector addition

of three individual A-F bonds is nonzero. In other words, the individual bond dipoles do not

cancel each other. An example is chlorine trifluoride .

Therefore, molecules (ii) and (iii) will have a non zero dipole moment.