Section 12.3 talks about mass spectral fragmentation patterns. The mass spectrum of a compound serves as a kind of “molecular fingerprint.” In other words, it serves as a kind of “molecular motif.” Each compound has its own distinctive fragmentation pattern. If you have 2 samples which are constitutional isomers having the same molecular weight, then you can determine the way in which the atoms were bonded by their fragments. In essence, we are working backwards to determine the bonding structure of the whole molecule from its individual fragments or ions. The mass spectrometer breaks up the molecule in different ways depending on how it was bonded. That is the main factor which affects the appearance of the graph obtained from this instrument—the bonding of the atoms within the molecule. The graph is called the mass spectrum and this is how the mass spectrum is read: the horizontal x axis tells us the mass-to-charge ratio of the molecule fragment m/z and the y axis tells us its percent abundance. The lightest
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This note was uploaded on 11/06/2010 for the course CHEM 10258 taught by Professor Dr.doodoohead during the Spring '10 term at Gwinnett Technical College.