Group Theory

Question 1

How can we predict the IR and Raman spectra of compounds?

Answer 1

Using symmetry operations.

Question 2

Define what -1, 1 and 0 mean in terms of each operation.

Answer 2

Change in axis: -1 per axis
No change in axis: +1 per axis
Atoms move: 0 per axis

Question 3

What are A and B?

Answer 3

A=symmetrical with respect to primary axis
B=anti-symmetrical with respect to primary axis.

Question 4

What is E? What is T?

Answer 4

E=Double degenerate
T=Triple degenerate

Question 5

What is g and what is u?

Answer 5

G (Gerade)=Symmetrical with respect to inverse
U (Ungerade)=Asymmetrical with respect to inverse

Question 6

What is the subscript 1 and 2?

Answer 6

1=Symmetric with respect to principle axis
2=Asymmetric with respect to principle axis

Question 7

What is ‘ and ‘’?

Answer 7

‘=Symmetric with respect to sigma h (horizontal reflection)
“=Asymmetric with respect to sigma h (horizontal reflection)