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