( ( Since ( ( the ( ( electron and ) proton ) ) ( have ( ( ( equal but ) opposite ) ( electrical charge ) ) ) ) ) ( , ( ( the ( neutral atom ) ) ( ( must ( contain ( ( an ( equal number ) ) ( of ( ( electrons and ) protons ) ) ) ) ) . ) ) ) )
(ROOT (S (SBAR (IN Since) (S (NP (DT the) (NN electron) (CC and) (NN proton)) (VP (VBP have) (NP (ADJP (JJ equal) (CC but) (JJ opposite)) (JJ electrical) (NN charge))))) (, ,) (NP (DT the) (JJ neutral) (NN atom)) (VP (MD must) (VP (VB contain) (NP (NP (DT an) (JJ equal) (NN number)) (PP (IN of) (NP (NNS electrons) (CC and) (NNS protons)))))) (. .)))
Since the electron and proton have equal but opposite electrical charge, the neutral atom must contain an equal number of electrons and protons.
(ROOT (S (SBAR (IN Because) (S (NP (NNS atoms)) (VP (VBP have) (NP (NP (JJ equal) (NNS numbers)) (PP (IN of) (NP (NP (JJ positive) (NNS protons)) (CC and) (NP (JJ negative) (NNS electrons)))))))) (, ,) (NP (PRP they)) (VP (VBP possess) (NP (DT a) (JJ neutral) (NN charge))) (. .)))