( ( A ( hydrogen atom ) ) ( also ( ( has ( one electron ) ) . ) ) )
(ROOT (S (NP (DT A) (NN hydrogen) (NN atom)) (ADVP (RB also)) (VP (VBZ has) (NP (CD one) (NN electron))) (. .)))
A hydrogen atom also has one electron.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD one) (NNS electrons)) (PP (IN in) (NP (DT the) (NN hydrogen) (NN atom))))) (. .)))