The formation of fragmentation patterns . . .
What the mass spectra of organic compounds look like, how the patterns are formed, and the sort of information you can get from them.
The molecular ion (M+) peak . . .
How the molecular ion peak can be used to find the relative formula mass of the compound and its molecular formula.
The M+1 peak . . .
How the M+1 peak arises, and its use in finding the number of carbon atoms a compound contains.
Organic compounds containing halogen atoms . . .
How the M+2 (and possibly M+4) peak arises, and its use in showing the presence of chlorine or bromine in a compound.