2 molecular spectroscopy

Question 1

what is molecular spectroscopy and what does it do

Answer 1

uses the interaction between electromagnetic radiation and matter to obtain info about molecules

Question 2

why is spectroscopy important

Answer 2

helps us find info about molecules
helps us identify compounds and how much of it is present (quantitative analysis)
bond lengths
bond angles
bond strength

Question 3

what does molecular energies being quantised mean

Answer 3

it means that they can only be certain, discrete values

Question 4

what is spectroscopy, based on quantised, discrete energy levels

Answer 4

spec involves the transition between then quantised, discrete energy levels

Question 5

what does discrete mean

Answer 5

individually separated and distinct
🌳🌳🌳🌳. 🌲

Question 6

what transition occurs in spec

Answer 6

the molecule transitioning between the quantised, discrete energy levels.

Question 7

explanation or IR spec absorption bands

Answer 7

when radiation is absorbed due to different bond vibration in the molecule

Question 8

speed of light
wavelength
frequency equation

Answer 8

c = wavelength x v

Question 9

energy of a photon
planks constant
frequency equation

Answer 9

E = hv

Question 10

what happens when a molecule absorbs a photon of energy

Answer 10

if this energy corresponds to the energy gap between initial and final energy levels, it transitions to a higher molecular energy level.

Question 11

what does the spacing between energy levels depend on

Answer 11

the type of molecular transition
- rotational is smallest distance
- vibrational is the middle distance
- electronic is the largest distance

Question 12

different molecular transitions eg: rotational, vibrational, electronic

absorb energy from…

Answer 12

different parts of the electromagnetic spectrum

Question 13

electronic transitions absorb radiation from which part of the electromagnetic spectrum

Answer 13

VISIBLE + UV

Question 14

molecular vibrations absorb radiation from which part of the electromagnetic spectrum

Answer 14

INFRARED

Question 15

molecular rotations absorb energy from which section of the electromagnetic spectrum

Answer 15

MICROWAVE
INFRARED

Question 16

electron spins absorb radiation from which part of the electromagnetic spectrum

Answer 16

MICROWAVES

Question 17

what part of the electromagnetic spectrum do nuclear spins absorb radiation from

Answer 17

radio waves

Question 18

which bit of the electromagnetic spectrum has the shortest wavelength

Answer 18

gamma rays (short WL, high V + E + V-)
x rays
UV
VIS
IR
microwaves
radio waves (large WL, small V, E, V- )

Question 19

what changes are x rays involved with

Answer 19

changes that occur in atomic nuclei

Question 20

what changes are UV and VIS involved in

Answer 20

transitions between electronic energy levels

Question 21

why do transitions between electronic energy levels need UV VIS radiation

Answer 21

bc the energy level gaps between electronic energy levels are the largest!!

they need more energy to transition to them

Question 22

infrared radiation is equivalent to what

Answer 22

transitions between vibrational energy levels
aka: equivalent to transitions involved in vibration of chemical bonds

Question 23

what do microwaves correspond to

Answer 23

energy level gap between rotational energy transitions.

aka; energy corresponding to the transitions when a molecule rotates

Question 24

what do radio waves correspond to

Answer 24

energy of transition associated when an electron or nucleus spins in a magnetic field.

Question 25

what happens to CO2 when it’s molecular vibration changes

Answer 25

bond lengths and angles change

it can do the splits, streamline
bonds can get shorter or longer

Question 26

what happens to CO2 when it’s molecular rotation changes

Answer 26

rotates - teddy bear roll

bond length and angle stays the same