( ( The ( hydrogen atom ) ) ( ( has ( ( ( ( one ( proton ( and ( one electron ) ) ) ) , ) but ) ( no neutron ) ) ) . ) )
(ROOT (S (NP (DT The) (NN hydrogen) (NN atom)) (VP (VBZ has) (NP (NP (CD one) (NN proton) (CC and) (NN one) (NNS electron)) (, ,) (CC but) (NP (DT no) (NN neutron)))) (. .)))
The hydrogen atom has one proton and one electron, but no neutron.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD one) (NNS electrons)) (PP (IN in) (NP (DT the) (NN hydrogen) (NN atom))))) (. .)))