( ( ( ( ( ( ( The ( atomic weight ) ) , ) or ) mass ) , ) ( of ( an element ) ) ) ( ( is ( ( the sum ) ( of ( all ( ( ( its protons ) and ) neutrons ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NP (DT The) (JJ atomic) (NN weight)) (, ,) (CC or) (NP (NN mass)) (, ,)) (PP (IN of) (NP (DT an) (NN element)))) (VP (VBZ is) (NP (NP (DT the) (NN sum)) (PP (IN of) (NP (PDT all) (NP (PRP$ its) (NNS protons)) (CC and) (NP (NNS neutrons)))))) (. .)))
The atomic weight, or mass, of an element is the sum of all its protons and neutrons.
(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)))) (. .)))