2B Analytical Methods

Question 1

For a mode of vibration to be IR active it must

Answer 1

Give rise to a change in the molecular electric dipole moment

Question 2

For a mode of vibration to be Raman active it must give rise to a change in

Answer 2

Polarizability

Question 3

The ease in which the electron cloud associated with the molecule is distorted

Answer 3

Polarizability

Question 4

For centrisymmetric molecules the rule of mutual exclusion states that

Answer 4

Vibrations that are IR active are Raman inactive and vice versa

Question 5

Mulliken Symbols: A

Answer 5

Symmetric with respect to rotation around the principal rotational axis

Question 6

Mulliken Symbols: B

Answer 6

Anti symmetric with respect to rotation around the principal rotation axis

Question 7

Mulliken Symbols: E

Answer 7

Doubly degenerate

Question 8

Mulliken Symbols: T

Answer 8

Triply degenerate

Question 9

Mulliken Symbols: subscript g

Answer 9

Symmetric with respect to center of symmetry. Sign of wavefunction does not change on inversion

Question 10

Mulliken Symbols: subscript u

Answer 10

Anti symmetric with respect to center. Sign of wavefunction changes on inversion

Question 11

Mulliken Symbols: subscript 1

Answer 11

Symmetric with respect to vertical mirror plane perpendicular to principal axis. Sign of wavefunction does not change upon rotation

Question 12

Mulliken Symbols: subscript 2

Answer 12

Anti symmetric with respect to vertical mirror plane perpendicular to principal axis. Sign of wavefunction changes upon rotation

Question 13

Mulliken Symbols: prime or ‘

Answer 13

Symmetric with respect to mirror plane horizontal to principal rotational axis

Question 14

Mulliken Symbols: double prime or “

Answer 14

Anti symmetric with respect to to a mirror plane horizontal to principal rotational axis

Question 15

The notation for electronic transitions shows the ____ energy level first

Answer 15

Higher

Question 16

Higher energy to lower energy level

Answer 16

Emission

Question 17

Lower energy level to higher energy level

Answer 17

Absorption

Question 18

Transitions may occur from singlet to sign,et or from triplet to triplet states and so on, but a change in spin multiplicity is forbidden

Answer 18

Spin selection rule ΔS = 0

Question 19

Laporte selection rule

Answer 19

There must be a change in parity

Question 20

Allowed transitions by Laporte

Answer 20

G to U

Question 21

Forbidden transitions by Laporte

Answer 21

G to G and U to U

Question 22

Allowed transitions by Δl = +/- 1

Answer 22

S to P, P to D, D to F

Question 23

Transitions forbidden by Δl = +/- 1

Answer 23

S to S, P to P, D to D, F to F, S to D, P to F, etc

Question 24

Wavelength red

Answer 24

620 to 700

Question 25

Wavelength orange

Answer 25

580 to 610

Question 26

Wavelength yellow

Answer 26

560-580

Question 27

Wavelength green

Answer 27

490-560

Question 28

Wavelength blue

Answer 28

439-490

Question 29

Wavelength violet

Answer 29

380-430

Question 30

Order of light spectrum

Answer 30

Gamma, X, UV, vis, IR, microwave, radio waves

Question 31

Energy difference between absorption and emission

Answer 31

Stokes shift

Question 32

If something is forbidden that means it is

Answer 32

Slow and less intense

Question 33

When an atom with an α spin state is exposed to radio waves with just the right energy, the photons are — and the spin —

Answer 33

Absorbed; flips to β

Question 34

The stronger the magnetic field, the — the energy gap

Answer 34

Greater

Question 35

Causes electrons to circulate, inducing an opposing magnetic field (diamagnetism)

Answer 35

B0

Question 36

Nuclei are shielded when they

Answer 36

Experience less B0

Question 37

Shielding requires — energy to spin flip

Answer 37

Less

Question 38

Nuclei surrounded by less electron density

Answer 38

Deshielded

Question 39

Number of lines on NMR

Answer 39

Multiplicity

Question 40

What determines multiplicity

Answer 40

Number and spins of the attached nuclei

Question 41

Vibrations linear molecule

Answer 41

3N - 5

Question 42

Nonlinear vibrations

Answer 42

3N - 6

Question 43

which end of the spectrum has the highest energy

Answer 43

left (gamma rays)

Question 44

which end of the spectrum has the higher frequency

Answer 44

left (gamma rays)

Question 45

which end of the spectrum has the longest wavelength

Answer 45

right (radio)

Question 46

irreducible representations are ___ to each other

Answer 46

orthogonal

Question 47

if all d transition spots are filled equally, is the spin allowed?

Answer 47

no