( ( ( An ( ( atom or ) molecule ) ) ( of ( a substance ) ) ) ( usually ( ( ( does not ) ( emit energy ) ) ; ) ) )
(ROOT (S (NP (NP (DT An) (NN atom) (CC or) (NN molecule)) (PP (IN of) (NP (DT a) (NN substance)))) (ADVP (RB usually)) (VP (VBZ does) (RB not) (VP (VB emit) (NP (NN energy)))) (: ;)))
An atom or molecule of a substance usually does not emit energy;
(ROOT (S (NP (NNP Energy)) (VP (VBZ is) (VP (VBN stored) (PP (IN in) (NP (NP (DT a) (JJ chemical) (NN substance)) (PP (IN between) (NP (NNS atoms))))))) (. .)))
Energy is stored in a chemical substance between atoms.