( ( ( ( A ( hydrogen-like atom ) ) or ) ( a ( hydrogenic atom ) ) ) ( ( is ( ( an atom ) ( with ( one electron ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (JJ hydrogen-like) (NN atom)) (CC or) (NP (DT a) (JJ hydrogenic) (NN atom))) (VP (VBZ is) (NP (NP (DT an) (NN atom)) (PP (IN with) (NP (CD one) (NN electron))))) (. .)))
A hydrogen-like atom or a hydrogenic atom is an atom with 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))))) (. .)))