"In the NMR spectra of aldehydes and ketones, the formyl hydrogens and the carbonyl carbons show strong deshielding. The carbon – oxygen double bond in ketones gives rise to a strong infrared band at about 1715cm-1, which is shifted to lower frequency by conjugation and to higher frequency in aldehydes and small rings. The ability of nonbonding electrons to be excited into the π* molecular orbitals causes the carbonyl group to exhibit characteristic, relatively long-wavelength UV absorptions. Finally, aldehydes and ketones fragment in the mass spectrometer by α cleavage and McLafferty rearrangement."