( ( atom ( ( A ( building block ) ) ( of ( ( matter , ) ( ( the ( smallest particle ) ) ( that ( has ( ( the ( chemical characteristics ) ) ( of ( a ( particular ( chemical element ) ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VB atom) (NP (NP (DT A) (NN building) (NN block)) (PP (IN of) (NP (NP (NN matter)) (, ,) (NP (NP (DT the) (JJS smallest) (NN particle)) (SBAR (WHNP (WDT that)) (S (VP (VBZ has) (NP (NP (DT the) (JJ chemical) (NNS characteristics)) (PP (IN of) (NP (DT a) (JJ particular) (NN chemical) (NN element)))))))))))) (. .)))
atom A building block of matter, the smallest particle that has the chemical characteristics of a particular chemical element .
(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)))) (. .)))