Homework 7

Name: ______________________________

Section: _____________________________

Student ID#:__________________________

Q1

Draw sketches to illustrate the following symmetry elements:

1. a vertical mirror plane and a $$C_2$$ axis in $$O_3$$ (ozone)
2. a horizontal mirror plane in $$CO_2$$
3. an $$S_4$$ axis in methane
4. all of the symmetry elements in $$CH_3F$$ (point group $$C_{3v}$$)
5. all of the symmetry elements in ethene (point group $$D_{2h}$$)

Q2

Determine the symmetry elements possessed by an $$s$$ orbital, a $$p$$ orbital, a $$d_{z^2}$$ orbital, and a $$d_{xy}$$ orbital.

Q3

Which of the following molecules has either i) a center of inversion or ii) an $$S_4$$ axis?

1. $$CO_2$$
2. $$C_2H_2$$
3. $$BF_3$$
4. $$SO_4^{2-}$$

Q4

Identify the symmetry elements in the following molecules, and assign each one to a point group

1. $$NH_2Cl$$
2. $$SiF_4$$
3. $$\ce{H-C#N}$$
4. $$SiFClBrI$$
5. $$NO_2$$
6. $$H_2O_2$$

Q5

1. What are the symmetry elements that prevent a molecule from being polar? Which of the molecules in Q4 are polar?
2. What are the symmetry elements that exclude chirality? Which (if any)of the molecules in Q4 may be chiral?