( ( ( isomer Any ) ( of ( two ( chemical substances ) ) ) ) ( ( composed ( of ( ( the ( same elements ) ) ( ( ( in ( the ( same proportions ) ) ) but ) ( with ( ( ( different structures ) and ) ( different properties ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NN isomer) (NNS Any)) (PP (IN of) (NP (CD two) (NN chemical) (NNS substances)))) (VP (VBN composed) (PP (IN of) (NP (NP (DT the) (JJ same) (NNS elements)) (PP (PP (IN in) (NP (DT the) (JJ same) (NNS proportions))) (CC but) (PP (IN with) (NP (NP (JJ different) (NNS structures)) (CC and) (NP (JJ different) (NNS properties)))))))) (. .)))
isomer Any of two chemical substances composed of the same elements in the same proportions but with different structures and different properties.
(ROOT (S (NP (NP (NNS Substances)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN broken) (PRT (RP down)) (PP (IN into) (NP (NP (JJR simpler) (NNS substances)) (PP (IN with) (NP (JJ different) (NNS properties))))))))))) (VP (VBP are) (VP (VBN called) (NP (NNS elements)))) (. .)))