( ( ( One piece ) ( of ( an element ) ) ) ( ( is ( called ( an atom ) ) ) . ) )
(ROOT (S (NP (NP (CD One) (NN piece)) (PP (IN of) (NP (DT an) (NN element)))) (VP (VBZ is) (VP (VBN called) (NP (DT an) (NN atom)))) (. .)))
One piece of an element is called an atom.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (NNS elements)) (SBAR (WHNP (WDT that)) (S (VP (VBP contain) (NP (NP (JJ only) (NNS atoms)) (PP (IN of) (NP (NP (CD one) (NN type)) (PP (IN of) (NP (NN element) (NN native) (NNS elements))))))))))) (. .)))