( ( ( ( the ( molecular mass ) ) ( -LRB- ( or ( ( molecular weight ) -RRB- ) ) ) ) ( of ( a compound ) ) ) ( ( is ( ( the sum ) ( of ( ( the ( atomic masses ) ) ( in ( ( one molecule ) ( of ( the compound ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (DT the) (JJ molecular) (NN mass)) (PRN (-LRB- -LRB-) (CC or) (NP (NP (JJ molecular)) (NP (NN weight))) (-RRB- -RRB-))) (PP (IN of) (NP (DT a) (NN compound)))) (VP (VBZ is) (NP (NP (DT the) (NN sum)) (PP (IN of) (NP (NP (DT the) (JJ atomic) (NNS masses)) (PP (IN in) (NP (NP (CD one) (NN molecule)) (PP (IN of) (NP (DT the) (NN compound))))))))) (. .)))
the molecular mass (or molecular weight) of a compound is the sum of the atomic masses in one molecule of the compound.
(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))))) (. .)))