( ( ( An atom ) ( of ( an element ) ) ) ( ( contains ( ( ( 63 protons ) and ) ( 89 neutrons ) ) ) . ) )
(ROOT (S (NP (NP (DT An) (NN atom)) (PP (IN of) (NP (DT an) (NN element)))) (VP (VBZ contains) (NP (NP (CD 63) (NNS protons)) (CC and) (NP (CD 89) (NNS neutrons)))) (. .)))
An atom of an element contains 63 protons and 89 neutrons.
(ROOT (S (S (VP (TO To) (VP (VB determine) (NP (NP (DT the) (JJ atomic) (NN weight)) (PP (IN of) (NP (DT an) (NN element))))))) (, ,) (NP (PRP you)) (VP (MD should) (VP (VB add) (PRT (RP up)) (NP (NNS protons) (CC and) (NNS neutrons)))) (. .)))