( ( Upon ( impact ( with ( a surface ) ) ) ) ( , ( ( the atoms ) ( ( ( release ( their ( stored energy ) ) ) ( to ( break ( chemical bonds ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN Upon) (NP (NP (NN impact)) (PP (IN with) (NP (DT a) (NN surface))))) (, ,) (NP (DT the) (NNS atoms)) (VP (VBP release) (NP (PRP$ their) (JJ stored) (NN energy)) (S (VP (TO to) (VP (VB break) (NP (NN chemical) (NNS bonds)))))) (. .)))
Upon impact with a surface, the atoms release their stored energy to break 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.