L3 Rich: IR spectroscopy part 2 Flashcards
what affects the position of bands in the IR spectrum?
mass of the atoms
strength of the bond
stronger the bond the ____ the _____
higher the frequency
the bigger the molecules the more?
complex the IR spectrum
what do we to do when we have large molecules?
do not try and assign specific vibrational modes
What to think when looking at IR of large molecules?
think of one or two bonds that are moving
what is key when looking at a large molecules IR spectrum?
Assign functional groups to specific frequencies
what region is looked at first when interpreting IR spectra?
the higher regions
1600+
what kind of peak is N-H?
sharp
what kind of peak is O-H?
It is broad (usually)
whats the lower region or IR and whats it also known as?
400 - 1600
fingerprint region
what peaks can sometimes be found in the fingerprint region?
c-cl
c-f
what number in the IR spectra shows a bond to hydrogen?
2500+
what happens when the mass is low?
vibrational frequency is high
what is the triple bond region?
2000- 2500
what region doesn’t usually have peaks and why?
2000-2500
the triple bond
as its uncommon
Name two triple bonds?
C—N
C—C
what stem double bond region?
1500- 2000
Name two double bonds?
C–O
C–N
which double bond peak has more intensity, C – O or C– N?
C – O
where’s the single bond region?
500 - 1500
what dominates the single bond region?
C-C
C-O
C-CL
Which single bond peak is intense?
C-CL
what do you need to do if you suspect theirs inorganic molecules?
look at an inorganic table provided
what do you need for an IR peak to be present?
covalent bond
what pea is usually at 2900?
C-H
