( ( An element ) ( ( is ( ( a ( basic substance ) ) ( consisting ( of ( atoms ( which ( ( are chemically ) alike ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT An) (NN element)) (VP (VBZ is) (NP (NP (DT a) (JJ basic) (NN substance)) (VP (VBG consisting) (PP (IN of) (NP (NP (NNS atoms)) (SBAR (WHNP (WDT which)) (S (VP (VBP are) (ADVP (RB chemically)) (ADJP (RB alike)))))))))) (. .)))
An element is a basic substance consisting of atoms which are chemically alike.
(ROOT (S (S (NP (NN Element)) (VP (VBZ is) (NP (NP (DT the) (JJ basic) (NN chemical) (NN building) (NN block)) (PP (IN of) (NP (NN matter)))))) (: ;) (S (NP (PRP it)) (VP (VBZ is) (NP (DT the) (JJS simplest) (NN chemical) (NN substance)))) (. .)))