2B Analytical Methods Flashcards

1
Q

For a mode of vibration to be IR active it must

A

Give rise to a change in the molecular electric dipole moment

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2
Q

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

A

Polarizability

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3
Q

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

A

Polarizability

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4
Q

For centrisymmetric molecules the rule of mutual exclusion states that

A

Vibrations that are IR active are Raman inactive and vice versa

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5
Q

Mulliken Symbols: A

A

Symmetric with respect to rotation around the principal rotational axis

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6
Q

Mulliken Symbols: B

A

Anti symmetric with respect to rotation around the principal rotation axis

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7
Q

Mulliken Symbols: E

A

Doubly degenerate

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8
Q

Mulliken Symbols: T

A

Triply degenerate

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9
Q

Mulliken Symbols: subscript g

A

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

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10
Q

Mulliken Symbols: subscript u

A

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

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11
Q

Mulliken Symbols: subscript 1

A

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

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12
Q

Mulliken Symbols: subscript 2

A

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

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13
Q

Mulliken Symbols: prime or ‘

A

Symmetric with respect to mirror plane horizontal to principal rotational axis

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14
Q

Mulliken Symbols: double prime or “

A

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

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15
Q

The notation for electronic transitions shows the ____ energy level first

A

Higher

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16
Q

Higher energy to lower energy level

A

Emission

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17
Q

Lower energy level to higher energy level

A

Absorption

18
Q

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

A

Spin selection rule ΔS = 0

19
Q

Laporte selection rule

A

There must be a change in parity

20
Q

Allowed transitions by Laporte

A

G to U

21
Q

Forbidden transitions by Laporte

A

G to G and U to U

22
Q

Allowed transitions by Δl = +/- 1

A

S to P, P to D, D to F

23
Q

Transitions forbidden by Δl = +/- 1

A

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

24
Q

Wavelength red

A

620 to 700

25
Q

Wavelength orange

A

580 to 610

26
Q

Wavelength yellow

A

560-580

27
Q

Wavelength green

A

490-560

28
Q

Wavelength blue

A

439-490

29
Q

Wavelength violet

A

380-430

30
Q

Order of light spectrum

A

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

31
Q

Energy difference between absorption and emission

A

Stokes shift

32
Q

If something is forbidden that means it is

A

Slow and less intense

33
Q

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

A

Absorbed; flips to β

34
Q

The stronger the magnetic field, the — the energy gap

A

Greater

35
Q

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

A

B0

36
Q

Nuclei are shielded when they

A

Experience less B0

37
Q

Shielding requires — energy to spin flip

A

Less

38
Q

Nuclei surrounded by less electron density

A

Deshielded

39
Q

Number of lines on NMR

A

Multiplicity

40
Q

What determines multiplicity

A

Number and spins of the attached nuclei

41
Q

Vibrations linear molecule

A

3N - 5

42
Q

Nonlinear vibrations

A

3N - 6