Mass and angular distributions of dijets produced in LHC pro ton-proton col- lisions at a centre-of-mass energy √ s = 7TeV have been studied with the ATLAS detector using the full 2011 data set with an integrated luminosity of 4.8fb − 1 . Dijet masses up to ∼ 4 . 0TeV have been probed. No resonance-like features have been observed in the dijet mass spectrum, and all angular distributions are cons istent with the predictions of QCD. Exclusion limits on six hypotheses of new phenomena hav e been set at 95% CL in terms of mass or energy scale, as appropriate. These hypothe ses include excited quarks below 2.83 TeV, colour octet scalars below 1.86TeV, heavy W bosons below 1.68 TeV, string resonances below 3.61 TeV, quantum black holes with s ix extra space-time dimen- sions for quantum gravity scales below 4.11 TeV, and quark co ntact interactions below a compositeness scale of 7.6 TeV in a destructive interferenc e scenario