Symmetry

Question 1

Symmetry element

Answer 1

Property of an object arsing from its shape

Question 2

Symmetry operation

Answer 2

Act of applying a symmetry element so the end point s indistinguishable

Question 3

Principle rotation axis

Answer 3

Highest order, Cn

Question 4

Horizontal mirror plane

Answer 4

Perpendicular to PRA

Question 5

Vertical mirror plane

Answer 5

Contains PRA

Question 6

Identity

Answer 6

E, all molecules possess this

Question 7

Improper rotation axis

Answer 7

S, rotate and reflect

Question 8

Inversion centre

Answer 8

I, each point moves through the inversion centre and out the other side

Question 9

Point group of very high symmetry molecules

Answer 9

Octahedral, Oh or tetrahedral, Td

Question 10

Point group of molecules with E only

Answer 10

C1

Question 11

Point group of molecules with E and mirror plane only

Answer 11

Cs

Question 12

Point group of molecules with E and I only

Answer 12

Ci

Question 13

How to determine point group

Answer 13

Check if high or low symmetry
Find PRA, C2 perpendicular = D, no C2 perpendicular = C
Has σh = h in subscript
Has σv but no σh, use v in subscript if Cn, d in subscript if Dn
No mirror planes = no letter in subscript

Question 14

Value f functions the same after applying symmetry operation

Answer 14

+1

Question 15

Value if functions changes positon but not sign or direction after applying symmetry operation

Answer 15

-1

Question 16

Value if function moves from original positon after applying symmetry operation

Answer 16

0

Question 17

Mulliken symbols: A/B

Answer 17

Singly degenerate

Question 18

Mulliken symbols: E

Answer 18

Doubly degenerate

Question 19

Mulliken symbols: T

Answer 19

Triply degenerate

Question 20

Mulliken symbols: A

Answer 20

Symmetric wrt PRA

Question 21

Mulliken symbols: B

Answer 21

Antisymmetric wrt PRA

Question 22

Mulliken symbols: subscript 1/2 means

Answer 22

Symmetry wrt any C2 axes perpendicular to PRA or f not present and σv

Question 23

Mulliken symbols: 1

Answer 23

Symmetric (+1)

Question 24

Mulliken symbols: 2

Answer 24

Antisymmetric (-1)

Question 25

Mulliken symbols: g/u meaning

Answer 25

Symmetry wrt inversion centre

Question 26

Mulliken symbols: g

Answer 26

Symmetric

Question 27

Mulliken symbols: u

Answer 27

Antisymmetric

Question 28

Mulliken symbols: ‘/“ meaning

Answer 28

Symmetry wrt σh

Question 29

Mulliken symbols: ‘

Answer 29

Symmetric

Question 30

Mulliken symbols: “

Answer 30

Antisymmetric

Question 31

What axis contains the PRA

Answer 31

Z axis