IR and mass spectronomy
All bonds vibrate at a characteristic frequency depending on the mass of the atoms, bond strength, and type of vibration
This is the infrared region of the electromagnetic spectrum
Infrared light will absorb some or all of the light at the frequencies at which its
bonds vibrate
'Fingerprint region'
More complicated and contains many signals so picking out functional groups is difficult
Unique for every compound
Can be compared to known samples to help identify it
Can also be checked to see if a compound is pure - should be identical. Any extra peaks are due to impurities
Identifying functional group signals
Used to spot characteristic signals for functional groups
C-H
2850 - 3000
3000 in unsaturated compounds, and <3000 in saturated compounds
O-H
very broad
carboxylic acids = 2500 - 3000
alcohols = 3200 - 3500
C=O
around 1700
aldehydes, ketones, carboxylic acids and esters
C=C
alkenes
small peak
around 1650
Mass spectronomy
Main stages
Ionisation
Acceleration
Deflection
Detection
Dalton's Atomic Theory
Elements are made of extremely small particles called atoms
Atoms of different elements can combine in whole number ratios
In chemical reactions, atoms are combined, divided, or rearranged
Used to identify atomic masses
After electron
bombardment, the majority of the ions formed have a +1 charge
Vaporisation
Fragmentation: molecular ions are broken up
Fragments may be responsible for other peaks found on the spectrum