( ( In ( a compound ) ) ( , ( ( ( the atoms ) ( of ( the ( constituent substances ) ) ) ) ( ( are ( ( connected atom-to-atom ) ( by ( chemical bonds ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (DT a) (NN compound))) (, ,) (NP (NP (DT the) (NNS atoms)) (PP (IN of) (NP (DT the) (JJ constituent) (NNS substances)))) (VP (VBP are) (VP (VBN connected) (NP (NN atom-to-atom)) (PP (IN by) (NP (NN chemical) (NNS bonds))))) (. .)))
In a compound, the atoms of the constituent substances are connected atom-to-atom by chemical bonds.
(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.