( ( The ( atomic weight ) ) ( ( is ( ( the number ) ( of ( ( ( protons and ) neutrons ) ( in ( the nucleus ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ atomic) (NN weight)) (VP (VBZ is) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS protons) (CC and) (NNS neutrons)) (PP (IN in) (NP (DT the) (NN nucleus))))))) (. .)))
The atomic weight is the number of protons and neutrons in the nucleus.
(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)))) (. .)))