7.1 & 7.2

Question 1

what is the molecular ion peak

Answer 1

indicated the species formed from the molecule by the loss of one electron

Question 2

what is fragmentation

Answer 2

when the molecular ion breaks into smaller pieces

Question 3

what does ‘ stand for in CH3’

Answer 3

a radical (unpaired electron)

Question 4

what is the base peak

Answer 4

the peak with the greatest abundance (most stable fragment)

Question 5

define infrared radiation

Answer 5

part of electromagnetic spectrum with frequencies below that of red light

Question 6

what is stretching

Answer 6

occurs when a bond absorbs infrared radiation and uses it to alter the length of the bond

Question 7

what is bending

Answer 7

bond angle increases and decreases

Question 8

what are the 3 things which vary the amount of energy a molecule absorbs

Answer 8

length of bond
strength of bond
mass of each atom in the bond

Question 9

what is absorption of infrared linked to

Answer 9

polarity (non-polar molecules do not absorb infrared radiation)

Question 10

what is transmittance

Answer 10

value in an infrared spectrum represents the amount of radiation absorbed at a particular wavenumber

Question 11

what is a wave number

Answer 11

infrared absorption represents the frequency of infrared radiation absorbed by a particular bond in a molecule

Question 12

what do weak intensities refer to in an infrared spectrum

Answer 12

high transmittance values (strong intensities to low transmittance values)

Question 13

what is the fingerprint region used for

Answer 13

identifying individual molecules as they all have a separate ‘fingerprint’

Question 14

give advantages and disadvantages of using chemical tests

Answer 14

+/ cheap
easily available
rapid results
-/ uses some of the sample which you can’t easily get back
they are not very sensitive