Or search: physics, unstable, activated, chemistry, responsive, oxidizable
2 Syllables: SU
abbess, active, Agnes, Atkins, axes, Bacchus, baggage, Baptist, blackish, blacksmith, brackish, cabbage, captive, happenings, lapses, napkins, package, Papists, practice, practise, Radcliffe, satis, taxes, trackless, waxes
3 Syllables: USU
adaptive, attractive, collapses, combative, establish, inactive, refractive, relapses, relaxes
4 Syllables: UUSU
interactive, reestablish, unattractive
5 Syllables: UUUSU
radioactive

Found 38 words across 4 groupings. Skipped 7 excess words of a similar stem.