( ( ( ( The number ) ( of ( ( protons and ) neutrons ) ) ) ( in ( an ( atomic nucleus ) ) ) ) . )
(ROOT (NP (NP (DT The) (NN number)) (PP (IN of) (NP (NNS protons) (CC and) (NNS neutrons))) (PP (IN in) (NP (DT an) (JJ atomic) (NN nucleus))) (. .)))
The number of protons and neutrons in an atomic nucleus.
(ROOT (S (S (S (VP (VBG Adding) (NP (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NNS protons)))) (CC plus) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS neutrons)) (PP (IN in) (NP (DT an) (NN atom))))))))) (VP (VBZ decides) (NP (PRP$ its) (JJ approximate) (NN mass)))) (: ;) (S (NP (JJ atomic) (NN number)) (VP (VBZ is) (NP (NP (DT another) (NN word)) (PP (IN for) (NP (DT this) (NN value)))))) (. .)))