( ( ( The smallest ) ( -LRB- ( and ( simplest -RRB- ) ) ) ) ( atom ( ( is ( ( Hydrogen , ) ( consisting ( of ( ( one Proton ) ( surrounded ( by ( one Electron ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NP (DT The) (JJS smallest)) (PRN (-LRB- -LRB-) (CC and) (ADJP (JJ simplest)) (-RRB- -RRB-))) (ADVP (RB atom)) (VP (VBZ is) (NP (NP (NNP Hydrogen)) (, ,) (VP (VBG consisting) (PP (IN of) (NP (NP (CD one) (NN Proton)) (VP (VBN surrounded) (PP (IN by) (NP (CD one) (NNS Electron))))))))) (. .)))
The smallest (and simplest) atom is Hydrogen, consisting of one Proton surrounded by 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))))) (. .)))