Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

chemistry 1A > spectroscopy > Flashcards

spectroscopy Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

order of electromagnetic radiation in order of decreasing wavelength

A

radio waves, microwaves, infrared radiation, visible light, ultraviolet light, x rays, gamma rays.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

visible spectrum wavelength range

A

390nm to 700nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

ground state electrons

A

electrons which have absorbed no energy and are in their lowest energy shell.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

excited electrons

A

electrons which have absorbed energy to promote them to higher energy shells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

wavelength and frequency equation

A

C = vλ
speed of light = frequency x wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

energy of a photon equation

A

E = hv
energy = plancks constant x frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Planck’s constant

A

6.626 x 10 ^-34 Js

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Avogadro’s constant

A

The number of atoms/ species in one mole
6.02 x 10^23 mol^-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

wavelength and wavenumber ratio

A

λ = 1/v*
v* in cm^-1 and λ in m so also use conversion rate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

frequency and period relationship

A

v = 1/T
frequency = 1 / period

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

period definition

A

the number of seconds per wave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

wavenumber

A

the number of waves per cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

electron volts to joules

A

1eV = 1.602 x 10 ^ -19 J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

relating energy and wavelength/ frequency equations

A

C = vλ and E =hv
v = C/λ
E = h(C/λ)
v* = 1/λ
E = hCv*

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

photon definition

A

Electromagnetic radiation which behaves as a particle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

frequency and energy rule for electromagnetic radiation

A

as the frequency increases the energy of electromagnetic radiation will increase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

rule for energy absorbed by an electron

A

the energy an electron will absorb is not the energy of the energy shell it is currently in or promoted to, it the the energy gap, or difference in energy between the two energy shells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Rydberg equation

A

E = RH/n^2
energy = Rydberg’s constant / (principal quantum number)^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Rydberg’s constant

A

RH = 13.6 eV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

energy gap of an electron equation

A

ΔE = RH( 1/n^2 - 1/ n^2)
where n = n1 and n = n2
n1< n2
basically the energy must be positive because its an energy gap

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

series of energy transitions

A

lyman : n =1
balmer : n = 2
paschen : n = 3
bracket : n = 4
pfund : n = 5
where n is the lower energy shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

basic quantum numbers of electrons

A

n , l , ml, ms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

n quantum number

A

the principal quantum number referring to electron energy shell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

l quantum number

A

the angular momentum quantum number shows the position and the momentum ( mass x velocity)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

ml quantum number

A

the magnetic quantum number - refers to the orbital orientation that the electron is occupying

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

ms quantum number

A

the spin magnetic quantum number - shows the electrons spin direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

orbital selection rule for promotion of electrons

A

electrons can only be promoted to orbitals with higher energy than their ground state with an angular momentum quantum number of l+1.
(this means if it is an s orbital it can only be promoted to higher energy p orbitals, and a p can only be promoted to higher energy d orbitals, ect)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

resolving power of a spectrometer equation

A

R = λ/Δλ
resolving power = wavelength of light measured / the smallest change in wavelength measurable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

resolving power definition

A

the measurement of how well a spectrometer can differentiate between different wavelengths

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

fine structure promotion explanation

A

when there is a very high resolving power spectrometer we can see orbital energy levels will fragment into smaller sub - energy levels.
This is because elections have a mass and a charge meaning they will produce a tiny magnetic field.
this magnetic field is shown by the ms quantum number.
The fine structure energy shell can be shown by the quantum number J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

fine structure quantum number equation

A

J = MS + L
total angular momentum for fine structure = spin magnetic quantum number + angular momentum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

hyperfine structure explanation

A

if you have an incredibly strong resolving power spectrometer you would see the transitions of fine structure energy levels will also fragment into smaller sub - sub shells of orbitals.
this is due to the nucleus which the electrons are attracted to having a mass and a charge meaning they will have a magnetic field.
this magnetic field will be shown by the I quantum number.
The hyperfine structure energy shell can be shown by the equation F = J + I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

nuclear angular momentum quantum number

A

I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

hyperfine structure quantum number equation

A

F = J + I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

beer lamber equation

A

A = ε[M]l
absorption = molar absorbance co efficient x concentration of absorbing species x path length
no units = L mol^-1 cm^-1 x mol L-1 x cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

transmittance equation

A

T = I/I0
transmittance = intensity detected /source intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

transmittance to absorption
absorption to transmittance

A

A = -log(T)
T = 10^-A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

limitations of beer lambert calculations accuracy

A

this equation is based on the assumption that all light is either absorbed or transmitted, and that neither of the container of the solution, or the solution will refelct any light.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

note on absorption and transmittance calculations

A

absorption cannot be directly transferred from a percentage to a decimal, must be converted to transmittance using T = 100 - %A. Then converted back using A = -log T

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

beer lambert equation of two different species which absorb the wavelength

A

A1 = l(ε1b1 x [B] + ε1c1 x [C])
A2 = l(ε2b2 x [B] + ε2c2 x [C])
then use simultaneous equations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

atomic absorption spectroscopy

A

a range of uv and visible electromagnetic radiation will be directed at a sample and specific wavelengths of light will be absorbed to promote electrons from to higher energy orbitals. this will reduce the transmission of these specific wavelengths which will detected by the spectrometer. this will cause black lines at absorbed wavelengths.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

atomic emmision spectroscopy

A

where electrons are excited to promote them to higher energy orbitals, this will allow the electron to relax and emit photons which will be detected by a spectrometer. the photons emitted will have an energy equal to the energy of the downwards transition of the electron.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

reason for a broad range of absorption for UV Vis spectrometry

A

a molecules electrons will have hyperfine and fine electron structures due to electron magnetic influence and nuclear magnetic influence on an orbital. These will cause a large variety of different energy gaps between the the different orbitals, meaning electrons can absorb a wider range of wavelengths of uv/ visible light to promote electrons to higher orbitals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

solvent rule for ranges of absorptions within UV and visible spectroscopy

A

solvents will bombard a solute molecule with electrons which will result in transitions of electrons to a broader range of absorption of wavelengths of UV / visible wavelengths of light.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

chromophore definition

A

a series of atoms within a molecule which will allow the molecule to absorb visible wavelengths of light.

46
Q

types of chromophore

A

conjugated system and weak field ligands in transition metal complexes.

47
Q

transition metal complexes defintion

A

a transition metal atom or ion which will accept non bonding electron pairs from a ligand by allowing them to occupy its d orbitals

48
Q

why do transition metals absorb visible light

A

Ligands form dative covalent bonds by filling unoccupied d orbitals with lone pairs, these lone pairs will repel the d orbitals which will split them from degenerate orbitals to higher and lower energy, which will result in visible wavelengths of light being absorbed to allow d - d transitions to occur.

49
Q

lower energy d orbitals

A

dxy, dxz, dyz

50
Q

higher energy d orbitals

A

d x2 - y2
dz2

51
Q

strong field ligands

A

a ligand which creates a large energy gap between the lower and higher d orbitals when splitting the d orbitals, resulting in UV light being absorbed by the metal complex.

52
Q

weak field ligands

A

a ligand which will create a small energy gap between the lower and higher energy d orbitals when splitting the d orbitals, which will result visible light being absorbed by the metal complex.

53
Q

rule for metal complexes colour

A

transition metal complexes will be coloured due to occupied d orbitals, other metal complexes will have no colour due to no d orbitals present.

54
Q

difference in geometric isomers absorption for UV visible spectroscopy

A

the E configuration will be a lower energy configuration than the Z configuration due to the groups with more electron density being on opposite sides of the molecule. this will result in there being a larger energy gap between the bonding and antibonding MO in E than in Z, which will result in a higher frequency and lower wavelength being absorbed by E than Z.
cis = Z trans = E

55
Q

electron transition feasibility rule

A

electron transition feasibility is based on the molar absorption co efficient ε
ε = [10^4, 10^6] allowed
ε = [10^3, 10^4] weakly allowed
ε = [0,10^3] forbidden

56
Q

key features affecting the molar absorption co efficient ε

A

the symmetry of the molecule

57
Q

bathochromic shift

A

where there is a shift to a larger wavelength and lower frequency (bathochromic)

58
Q

hypsochromic shift

A

where there is a shift to a lower wavelength and higher energy/ frequency (blue)

59
Q

hyperchromic shift

A

an increase in the molar absorption co efficient

60
Q

hypochromic shift

A

a decrease in the molar absorption co efficient

61
Q

effect of an electrophilic substituent to a symmetric molecule in UV visible spectroscopy.

A

the substituent will reduce the symmetry which will cause a hyperchromic shift.
the electrophile will remove electron density from the original molecule which will result in a bathochromic shift.

62
Q

nucleophilic substituent added to the symmetric molecule in UV / visible spectroscopy

A

the substituent will reduce symmetry which will increase the molar absorption co efficient causing a hyperchromic shift.
the nucleophile will add electron density to the molecule which will cause a hypsochromic shift.

63
Q

pH effect

A

increasing the pH means adding a base or adding a nucleophile - so hypsochromic shift.
decreasing the pH means adding an acid or adding an electrophile - so a bathochromic shift.

64
Q

IR spectrometry principle

A

bonding electrons will absorb IR radiation to enter different vibrational states allowing for the bonds to vibrate at a higher frequency

65
Q

diatomic molecules vibration modes

A

stretching

66
Q

polyatomic molecules vibration modes

A

bending and stretching

67
Q

factors affecting the frequency of IR absorbed by the bond

A

bond strength
masses of atoms involved in the bond

68
Q

bond strength effect on frequency of IR absorbed

A

as the bond strength increases the frequency of IR will increase

69
Q

mass of different atoms involved in bond effect on IR absorbed

A

as the masses of the atoms increases the frequency of IR absorbed will decrease.

70
Q

reduced mass formula

A

(m1 x m2)/ (m1 + m2 )

71
Q

frequency of IR absorbed formula

A

v = 1/2π x sqrt(k/μ)
frequency = 1/2π x sqrt(force constant / reduced mass)

72
Q

force constant units

A

kg N m^-1

73
Q

normal modes of linear polyatomic molecules

A

3N -5

74
Q

normal modes of non linear poly atomic molecules

A

3N -6

75
Q

IR active normal mode definition

A

a normal mode which can be detected on an IR spectrometer due to there being a change in the dipole moment of the molecule.

76
Q

normal mode definition

A

where a bond within a molecule will absorb infrared radiation of a specific wavenumber to produce a unique vibration.

77
Q

vibrational energy level equation

A

Ev = (V + 1/2)hv
vibrational energy = (vibrational energy level + 1/2) x Plancks constant x frequency

78
Q

boltzmanns equation

A

n1/n0 = exp[-(E-E)/kT)

79
Q

important property of nuclei for NMR

A

nuclei have a charge, mass and angular momentum meaning they will produce their own magnetic moment.

80
Q

magnetic moment definition

A

The magnetic field produced by a particle

81
Q

NMR process

A
  1. nuclei will have different orientations.
  2. an external magnetic field will cause the nuclei to align parallel or antiparallel to the external magnetic field, due to their magnetic moment.
  3. antiparallel is the high energy conformation and parallel is the low energy conformation.
  4. radio frequency electromagnetic radiation will be directed at a sample and specific frequency will be absorbed to allow nuclei in the parallel conformation to flip to the antiparallel orientation.
  5. the frequency absorbed will be detected by the spectrometer and recorded.
  6. The chemical shift will be calculated by measuring the radio frequency absorbed by the standard chemical TMS and using the formula
    δ = (vsample - v standard)/ v standard
    this is done to remove the variable of different strengths of magnetic field.
82
Q

nuclear angular momentum quantum number

A

I

83
Q

identifying the nuclear angular momentum

A

nuclear angular momentum will have a specific value for each different type of nuclei, which is a fixed property.

84
Q

magnetic moment of a nucleus requirement

A

I ≠ 0

85
Q

important nuclei angular momentums

A

12C = 0
1H = 1/2
13C = 1/2

86
Q

MI quantum number

A

the magnetic nuclear quantum number - which refers to the orientation of the nucleus.

87
Q

MI values

A

MI goes up in 1/2 from -I and I

88
Q

energies of nuclei with different MI

A

nuclei of the same type with different MI quantum numbers will be degenerate in normal environments but have different energies in an external magnetic field.

89
Q

external magnetic field symbol

A

B(naught)

90
Q

magnetic moment formula

A

μ = Yn x I*

91
Q

number of MI values

A

number of MI = 2I + 1

92
Q

bold I formula

A

I* = h*(1+I)I

93
Q

energy of a nucleus equation

A

E = -μ x B(naught)

94
Q

change in energy between nuclear conformations equation

A

ΔE = h*B(naught) x yn

95
Q

local magnetic field

A

the magnetic field which is acting on the nucleus

96
Q

electron effect on local magnetic field

A

electrons also have a mass charge and angular momentum so will also have a magnetic moment (Bind) which will reduce the effect of the external magnetic field on the nucleus

97
Q

change in energy between nuclear conformations equation including shielding

A

ΔE = h* yn x B(nought) x (1 - δH)

98
Q

reason for chemical shift

A

to remove the variable of magnetic field strength to allow for universal comparison of spectroscopies.

99
Q

chemical shift formula

A

δ = (vsample - vstandard)/v spec

100
Q

chemical shift units

A

parts per million because the difference on the top will be approximately 1 million times smaller than the number on the bottom.

101
Q

range of chemical shift

A

from 0 - 12ppm

102
Q

greater electron shielding effect on chemical shift

A

greater electron shielding will result in a weaker local magnetic field, which will reduce the energy gap between the parallel and antiparallel conformation, which will result in a lower frequency being absorbed and a smaller chemical shift.

103
Q

weaker electron shielding effect on chemical shift

A

weaker electron shielding will result in a stronger local magnetic field, which will increase the energy gap between the parallel and antiparallel conformation, which will result in a higher frequency being absorbed and a larger chemical shift chemical shift.

104
Q

electronegativity effect on chemical shift

A

an electronegative group will remove electron density from the nucleus reduce the electron shielding and increase local magnetic field, increasing the energy gap between nuclei conformations increasing frequency absorbed and chemical shift.

105
Q

number of substituents effect on chemical shift

A

as the number of substituents increases the original effect on the chemical shift will increase.

106
Q

effect of the distance of a substituent from the nucleus

A

as the substituent gets further from the nucleus the original effect on the chemical shift will decrease.

107
Q

hybridisation effect on chemical shift

A

As the distance between electron density in the molecule increases the deshielding effect will increase which will mean a stronger local field and a stronger chemical shift.
sp2>sp>sp3

108
Q

delocalization effect on chemical shift

A

delocalized pi electrons will create a current due to the free flow of electrons. this will produce a magnetic field which acts in the same direction as the external magnetic field increasing the chemical shift.

109
Q

intermolecular forces effect on chemical shift

A

hydrogen bonding will remove electron density from a nucleus using an electronegative atom, which will result in a deshielding effect and stronger local magnetic field, meaning a larger energy gap and greater chemical shift.

110
Q

intramolecular forces effect on chemical shift

A

covalent bond formed between the electrophile and the nucleus will remove electron density, which will increase chemical shift
covalent bond formed between a nucleophile will add electron density which will decrease chemical shift.

chemistry 1A (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions