( ( ( element ( A substance ) ) ( composed ( of ( atoms ( with ( the ( same ( atomic number ) ) ) ) ) ) ) ) ( ; ( ( ( can not ) ( be ( ( broken down ) ( in ( ordinary ( chemical reactions ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NP (NP (NN element)) (NP (DT A) (NN substance))) (VP (VBN composed) (PP (IN of) (NP (NP (NNS atoms)) (PP (IN with) (NP (DT the) (JJ same) (JJ atomic) (NN number))))))) (: ;) (VP (MD can) (RB not) (VP (VB be) (VP (VBN broken) (PRT (RP down)) (PP (IN in) (NP (JJ ordinary) (NN chemical) (NNS reactions)))))) (. .)))
element  A substance composed of atoms with the same atomic number ; cannot be broken down in ordinary chemical reactions.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT a) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN broken) (PRT (RP down)) (PP (TO to) (NP (JJ other) (NNS substances))) (PP (IN by) (NP (NP (NN chemical) (NNS reactions)) (NP (DT an) (NN element))))))))))) (. .)))