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Drug structure > spectrometry > Flashcards

spectrometry Flashcards

1
Q

equation to calculate the energy of a photon

A

E=hv

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2
Q

beer lambert law

A

A=ecl

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3
Q

describe electromagnetic radiation diagram

A

electric field on y axis then magnetic field towards/away from me

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4
Q

what is Hz

A

cycles per second/ s^-1

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5
Q

equation with wavelength and frequency

A

wavelength is inversely proportional to frequency,
λ ∝1/ν

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6
Q

wavelength symbol

A

λ

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7
Q

frequency symbol

A

v

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8
Q

speed of light equation

A

c = νλ
speed of light in a vacuum= 3x10^8 ms^-1

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9
Q

describe the visible colour spectrum

A

purple————>red
higher frequency, shorter wavelength, higher energy

lower frequency, longer wavelength, lower energy

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10
Q

how to calculate energy of a photon

A

E=hv
h is Planck’s constant
v is frequency

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11
Q

what is h when calculating energy of a photon

A

Planck’s constant

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12
Q

what is spectroscopy

A

study of interaction between electromagnetic radiation and matter

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13
Q

explain spectroscopy in general terms

A
  1. EMR with specific frequency is absorbed by molecule
  2. molecule becomes excited
    (higher frequency=higher energy)
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14
Q

explain UV/visible spectroscopy

A
  1. EMR in uv/vis range of frequencies has energy corresponding to electronic transitions
  2. when uv/vis radiation of specific frequency is absorbed, an electron is promoted to a higher energy level
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15
Q

what is an orbital

A

region of space that can hold up to 2 electrons with opposite spin (know drawing)

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16
Q

what are the shape of S and d orbitals

A

s- spherical
d- dumbbell (x y z)

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17
Q

what is refraction

A

when light slows down

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18
Q

photon energy diagram stuff

A

each transition has a different change in energy so absorbs a photon of different frequency, shorter wavelength=higher change in energy of photon

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19
Q

what is the λmax

A

wavelength at which the sample has the highest absorbance

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20
Q

describe a uv/vis spectrum graph

A

-absorbance on y axis and wavelength on x axis

-wavelength of uv light is varied

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21
Q

difference between absorption and emission

A

absorption- energy absorbed from photon will increase energy

emission- photon given out so energy decreases

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22
Q

why are broader absorptions observed when molecules are more complex

A

extra vibrational and rotational energy levels

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23
Q

difference between atomic and molecule spectrums

A

atoms have sharp spectra and molecules have broader spectra due to vibrational and rotational energy levels

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24
Q

why is the spectra of molecules broader than atoms

A

molecules have contribution of vibrational and rotational energy levels

25
Q

what is transmittance (T)

A

fraction of light intensity which passed through a sample unchanged

26
Q

how to calculate absorbance

A

absorbance= -log10(T)

27
Q

what is absorbance proportional to

A

concentration and path length of a sample

28
Q

what is e in beer lamberts law

A

molar absorptivity= absorbance of a 1 mol dm-3 sample with path length 1cm at a specific wavelength

29
Q

how to calculate transmittance through a sample

A

light after/light before

30
Q

what is beer lamberts law

A

A=ecl

31
Q

units of e

A

dm3mol-1cm-1

32
Q

how to find E on a beer lamberts graph

A

gradient/path length

33
Q

describe how infrared spectroscopy works

A
  1. bonds/bond angles vibrate with a specific frequency
  2. vibrational frequency depends on bond strength and atom mass
  3. difference in energy between vibrational energy levels match the infrared part of the electromagnetic spectrum
  4. when absorbing IR radiation, vibrations increase in amplitude
    (more vibrations=more energy)
34
Q

what is wave number and the symbol for it

A

number of waves per unit distance, ṽ

35
Q

what is wavenumber equivalent to

A

ṽ =1/λ
wavenumber= 1/wavelength

36
Q

what happens to bond strength and size as frequency increases

A

bond strength increases and size decreases

37
Q

what is the wavenumber of OH

A

3200-3600

38
Q

what is the wavenumber of COOH

A

2500-3300

39
Q

what is the wavenumber of C-H

A

2850-3100

40
Q

what is the wavenumber of C=O

A

1630-1820

41
Q

what is Bo

A

magnetic field experienced by a nucleus

42
Q

what can cause a spin flip transition and where does the energy required come from

A

a photon of appropriate energy causes a spin flip, energy depends on the beff

43
Q

what is B elec

A

tiny magnetic field generated by electrons, B elec opposes the external magnetic field Bo

44
Q

describe the relationship between Bo and Belec and nucleus

A

Belec opposes Bo so the nucleus experiences a weaker magnetic field than Bo, electrons shield the nucleus from Bo, greater electron density, greater shielding effect

45
Q

what do electronegative elements do

A

attract electron density from adjacent groups

46
Q

what is beff

A

effective magnetic field, magnetic field felt by each atom, different for each atom therefore the change in energy is different and different energy photons absorbed, greater electron density lower beff

47
Q

how does electron density affect b eff

A

greater electron density=increased shielding=lower b eff
because more b elec to oppose b o
change in energy is lower and a lower energy photon is absorbed

48
Q

what is the ppm of aromatic protons

A

7-8

49
Q

what do the number of signals/peaks in H nmr represent

A

number of proton environments in a molecule

50
Q

what is integration number in H nmr

A

ratio of number of protons in each environment, area under signal, number of H in the environment

51
Q

what is multiplicity

A

signal shape (singlet,doublet,triplet), tells you number of protons in adjacent environments, N+1, if 2 protons in adjacent environment then it is a triplet

51
Q

what does mass spectrometry measure and how do is work

A

measures the mass to charge ratio of ions

  1. ionise sample which may cause molecule to fragment
  2. ions separated according to m/z
  3. ions detected
51
Q

what are coupling constants

A

3J 4J, how many jumps it takes to reach next proton (?)

51
Q

things to look at when interpreting H nmr

A

chemical shift, integration, splitting

51
Q

how to do an elemental analysis

A

percentage of each element divided by mass, divide by smallest value, ratio

51
Q

what is the molecular ion peak

A

peak with the highest m/z

52
Q

isotope pattern difference between chlorine and bromine

A

1:1 pattern indicates presence of bromine, 3:1 indicates presence of chlorine

52
Q

how to determine the molecular weight of a compound from a mass spec

A

the peak with the highest m/z value is the mass of the compound (molecular ion peak)

Drug structure (4 decks)

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