electronic spectroscopy + IR

Question 1

photoelectron spectroscopy has enough energy to do what

Answer 1

enough energy to ionise

Question 2

what is einsteins equation involving hv

Answer 2

planks x frequency =
ionisation energy x kinetic energy

Question 3

what does hv = Ke + Ie tell us

Answer 3

that if we know a photons energy and it’s kinetic energy, we can find it’s ionisation energy

Question 4

what is the process of photoelectron spectroscopy

Answer 4

shining hv on a sample ionised it and causes it to lose an electron

Question 5

what is hv

Answer 5

energy of a photon

Question 6

what does XPS stand for

Answer 6

x-ray photoelectron spectroscopy

Question 7

what is x-ray photoelectron spectroscopy used for + characteristics

Answer 7

• identifying chemical elements present and their environments
• quantitative
• surface selective

Question 8

ratio of surface to bulk

Answer 8

1 : 10^8

Question 9

electronic spectrum of the H atom emission spec diagram exp

Answer 9

promoted electron falls to lower energy level and emits a photon.

light is seen as this occurs.

Question 10

what is an alpha transition

Answer 10

lowest energy transition
the energy level right above the ground state

Question 11

what is the alpha transition for the lyman series

Answer 11

2

Question 12

what is the alpha transition for the ballet series

Answer 12

3

Question 13

what is the alpha transition of the paschen series

Answer 13

4

Question 14

what is the series limit transition

Answer 14

energy when electron falls from infinity to ground state

highest energy transition

Question 15

what light is lyman

Answer 15

UV
level 1

Question 16

what light is balmer

Answer 16

visible light
level 2

Question 17

what light is paschen

Answer 17

infrared light
level 3

Question 18

what does the series limit correspond to

Answer 18

the ionisation energy

Question 19

from the alpha transmission to the series limit transition, what happens to the energy spaces between then

Answer 19

they get smaller
the energy difference is smaller

Question 20

when light emitted is plotted against energy where does each series go

Answer 20

paschen = smallest energy, all lines have the same light intensity

balmer = middle, all lines have the same light intensity

lymann = highest energy, the same light intensity

Question 21

in hydrogen atom emission spectra, what series had the highest wavelength

Answer 21

lymann = shortest
balmer = middle
paschen = longest

Question 22

what is the rydberg equation for v- aka wavenumber

Answer 22

Rh = (1/smaller n2 - 1/larger n2 )

Question 23

rydberg constant value and units

Answer 23

1.097 x 10^5 cm-1

Question 24

what is the n1 aka smallest n value for the different series when finding v- wavenumber using the rhydberg equation

Answer 24

lymann = 1
balmer = 2
paschen = 3

these are the lowest energy levels the electron can fall to.

Question 25

what is n2 aka the largest number that an electron can fall from for each series

Answer 25

infinity

Question 26

worded rhydberg equation

Answer 26

wavenumber = rhydberg constant x (1/ where e- is falling to squared) - (1/ where electron is falling from squared) in cm-1

Question 27

infinity 2 gives what value

Answer 27

0

Question 28

what happens in UV VIS spec

Answer 28

absorbance of light or radiation excited electrons from group state to the first excited stage of the compound. go to the anti binding orbital??

Question 29

isobestic point

Answer 29

no intermediates molecule / state changes to another directly seen in UVVIS spec

Question 30

IR radiation can do what to molecules

Answer 30

cause a shape change stretch and bend them.

Question 31

when an atom is pulled apart to its max it has what

Answer 31

maximum extension LARGE POTENTIAL ENERGY

Question 32

when an atom is at its normal bond length is has

Answer 32

minimum extension minimum potential energy??

Question 33

r is theeee

Answer 33

the bond length

Question 34

what is the harmonic oscillator

Answer 34

U shape shows relationship between potential energy and r (bond length)

Question 35

harmonic oscillator explanation

Answer 35

as bond distance increases, potential energy decreases to a trough then increases again

Question 36

we can only oscillate smt atttt

Answer 36

particular energies

Question 37

what is oscillation

Answer 37

back and fourth rhythmic movements

Question 38

vibrational energy is

Answer 38

quantised

Question 39

equation to show how vibrational energy is quantised at energy level V

Answer 39

Ev = hw ( v + 1/2) where v is a quantum number for vibrational level (1,2,3,4) h is planks constant w is fundamental frequency (s-1)

Question 40

energy for vibrational level 1

Answer 40

E1 = h w (1 + 1/2 ) = 1.5 hw

Question 41

what is hw

Answer 41

fundamental frequency

Question 42

when energy is plotted against distance u get a parabola for potential energy. the distance between vibrational levels is

Answer 42

hw

Question 43

zero point energy

Answer 43

V=0 E0 = hw (0 + 1/2) = 1/2 hw this is bc a molecule cannot have 0 vibrational energy

Question 44

change in energy between 2 diff vibrational energy levels

Answer 44

Change in E = final - initial values values = answers to Ev = hw (V + 1/2 )

Question 45

what is w and it’s units

Answer 45

fundamental frequency s-1

Question 46

how can we find the fundamental frequency, w

Answer 46

W = 1/2🥧 x 🟫🌳 k/ reduced mass

Question 47

k is the

Answer 47

force constant aka strength or the spring

Question 48

if there’s a larger k value that means there is a larger

Answer 48

w value

Question 49

what is reduced mass for a bond between 2 diff molecules // 2 of the same molecules in kg

Answer 49

(M1)(M2) / M1 + M2

Question 50

when finding the M1 and M2 what must we do

Answer 50

mass of atom / avogadros constant then apply it to M1 and M2

Question 51

selection rule for IR SPEC

Answer 51

gross selection rule

Question 52

what is the gross selection rule

Answer 52

in order to interact with infrared radiation, a vibration must have a changing dipole

Question 53

how many independent directions can an atom move in

Answer 53

3 along the x, y, z axis

Question 54

total degrees of freedom = 3N

Answer 54

where n is the number of atoms.

Question 55

what is the other specific selection rule

Answer 55

in a simple harmonic oscillator, the change in V can only be -+1 u cannot jump 2 levels