spectroscopy and analysis Flashcards

1
Q

what is the frequency of an electromagnetic radiation?

A

cycles per second

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2
Q

relationship between wavelength and frequency?

A

wavelength inversely proportional to frequency

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3
Q

what is the speed of light in a vacuum?

A

3 × 10^8 ms^-1

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4
Q

how to calculate speed of light?

A

c= wavelength * frequency

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5
Q

what does a higher frequency on a visible colour spectrum mean?

A

the higher the frequency the shorter the wavelength
therefore the higher the energy

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6
Q

what is the order of electromagnetic spectrum form higher to lower energy (shorter to longer wavelength)?

A

gamma, X-ray, UV, infra-red, microwave, radio

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7
Q

what is the energy of photons given by?

A

E=hv
h is Planck’s constant

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8
Q

what is the value of Planck’s constant?

A

6.626 × 10^-34 m^2 kg s−1

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9
Q

what happens during spectroscopy?

A

EMR with specific frequency is absorbed by molecule which then becomes excited

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10
Q

does electromagnetic radiation have a range of frequencies corresponding to what?

A

electronic transitions

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11
Q

what happens to the electron after radiation is absorbed?

A

electron promoted to a higher level

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12
Q

what is an orbital?

A

region of space that can hold a maximum of two electrons with opposite spins

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13
Q

when will hydrogen atoms absorb photons?

A

hydrogen atoms will absorb photons with frequencies that agree with the differences between energy levels

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14
Q

what is λmax?

A

wavelength that a sample has the highest absorbance

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15
Q

why are absorption broader as molecules become more complex?

A

more vibrations and rational energy levels

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16
Q

what happens as conjugation increases?

A

gaps between HOMO and LUMO increases

17
Q

difference between atomic and molecular absorption?

A

atoms have a sharp spectra
molecules have

18
Q

what is transmission?

A

fraction of light intensity that has passed through a sample unchanged

19
Q

what is the equation of absorbance (A)?

A

A=-log T

20
Q

what is the equation of transmittance?

A

T= I/I0

21
Q

what is lamberts law?

A

A proportional the l
l (path length)

22
Q

what is the beer lamber law?

A

A is proportional to c
c (concentration)

23
Q

what is the beer lambert equation?

A

A= εcl

24
Q

what is molar extinction?

A

the absorbance of 1 mol dm-3 sample with path length on 1cm

25
Q

what layout does the beer lambert equation have?

A

A= εl * c
y= m * x

26
Q

how can a bond be approximated?

A

spring between two spheres

27
Q

equation for wavelength (ṽ)?

A

ṽ =1/λ

28
Q

what does a high wavelength mean?

A

high frequency

29
Q

what does increasing bond strength between two spheres do?

A

increasing bond strength increases frequency

30
Q

what does decreasing size of spheres do?

A

increases frequency

31
Q

what are the two components of electromagnetic radiation?

A

magnetic field going in the x-axis
electric field going in the y-axis

32
Q

what is a photon?

A

little packet of energy that goes in the same direction as light

33
Q

what is spectroscopy defintion?

A

‘study of the interaction between
electromagnetic radiation and matter’

34
Q

what is monochromator?

A

one colour with a specific wavelength is split

35
Q

where are the electrons in an orbital

A

orbital is where 95% of the electrons will be found

36
Q

why are electrons further away from the nucleus harder to remove?

A

electrons further away form the nucleus are harder to remove because they’re at a higher energy level

37
Q
A

‘the difference between energy in vibrational energy levels matches the infra-red part of the electromagnetic spectrum’

38
Q

what happens to a bond when it absorbs photons?

A

when bonds absorb photons its amplitude increases
frequency remains the same

39
Q
A

doubling concentration doubles absorbance