( ( ( The mass ) ( of ( an atom ) ) ) ( ( is ( given ( by ( ( the sum ) ( of ( ( the ( ( protons and ) neutrons ) ) ( in ( the ( atomic nucleus ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (NN mass)) (PP (IN of) (NP (DT an) (NN atom)))) (VP (VBZ is) (VP (VBN given) (PP (IN by) (NP (NP (DT the) (NN sum)) (PP (IN of) (NP (NP (DT the) (NNS protons) (CC and) (NNS neutrons)) (PP (IN in) (NP (DT the) (JJ atomic) (NN nucleus))))))))) (. .)))
The mass of an atom is given by the sum of the protons and neutrons in the atomic nucleus.
(ROOT (S (NP (NP (DT The) (NN sum)) (PP (IN of) (NP (NP (DT the) (NNS masses)) (PP (IN of) (NP (NP (DT the) (NNS atoms)) (PP (IN in) (NP (DT the) (NN formula)))))))) (VP (VBZ is) (VP (VBN referred) (PP (TO to) (NP (RB as) (JJ molecular) (NN mass))))) (. .)))