Take #"methyl chloride"# versus #"ethyl chloride"# versus #"isopropyl chloride"# versus #"tert-butyl chloride"#, i.e. #H_3C-Cl#, #H_3C-CH_2Cl#, #(H_3C)_2CHCl#, #(H_3C)_3C-Cl#, and treat each reagent in turn with sodium hydroxide in some suitable solvent.
Now all of these species could conceivably react under given condtions with sodium hydroxide to give the alcohol #ROH# and #NaCl#.
Under conditions where associative (bond-making) reactivity was favoured, methyl chloride would by far the most reactive substrate in that there is less substitution, less #"steric bulk"#, less #"shrubbery"#, about the reactive centre. And under these conditions, #"tert-butyl chloride"#, would be quite inert because the incoming nucleophile is physically prevented, i.e. sterically hindered, from approaching the ipso carbon and making a #C-O# bond.
There should be many examples of steric versus electronic effects in your organic text.
