sentence2_structure: objects<>are<>atomic/subatomic$$$The specialized study of the motion of objects<>is called<>quantum mechanics
sentence1: Quantum mechanics is a set of principles describing physical reality at the atomic level of matter (molecules and atoms) and the subatomic (electrons, protons, and even smaller particles).
sentence2: The specialized study of the motion of objects that are atomic/subatomic in size is called quantum mechanics.
question: The specialized study of the motion of objects that are atomic/subatomic in size is called what?