4.4 Physical & Chemical Changes

Physical changes (melting, dissolving molecular solids) overcome IMFs; the substance's identity stays. Chemical changes break and form chemical bonds and create new substances.

Dissolving ionic salts is a gray zone — ionic bonds break, but AP generally treats it with care; justify with particle reasoning.

New substance = chemical. Same substance, new state = physical.

Worked example: Burning wax is chemical; melting wax is physical.