Chapter 13 Muddiest Point

My muddiest point from chapter 13 is interpreting infared spectrums. I understand no observable data can be retrieved from the fingerpoint region. My main misunderstanding is how carbonyl groups are located on the spectrum. I know that each absorption depends on the particular types but do not understand how rings and double bonds are identified. I found in chapter 21 that aldehydes and ketones give a strong peak at 1700 due to the C-O double bond. I also found that the sp3 hybridized C-H bond of an aldehyde shows one or two peaks at 2700-2830. These exact positions of the carbonyl absorptions provide additional information about a compound. For example, most aldehydes have a C-O double bond peak around 1730 and ketones peak around 1715. The carbonyl absorption of cyclic ketones shifts to a higher wavenumber as the size of the ring decreases and the ring strain increases. Weaker bonds absorb at a lower frequency on the spectrum. After reading this section of chapter 21, I understand more about how to interpret carbonyl groups on infared spectrums.