( ( A ( chemical element ) ) ( ( is ( ( any substance ) ( that ( ( can not ) ( be ( ( separated ( into ( different substances ) ) ) ( except ( by ( radioactive decay ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (NN chemical) (NN element)) (VP (VBZ is) (NP (NP (DT any) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN separated) (PP (IN into) (NP (JJ different) (NNS substances))) (PP (IN except) (PP (IN by) (NP (JJ radioactive) (NN decay))))))))))) (. .)))
A chemical element is any substance that cannot be separated into different substances except by radioactive decay.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (DT a) (JJ pure) (NN substance)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB be) (VP (VBN broken) (ADVP (RB down) (PP (IN into) (NP (NP (JJ different) (NNS types)) (PP (IN of) (NP (NNS substances)))))) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN element))))))))) (. .)))