( ( Ozone ( -LRB- ( ( 0 3 ) -RRB- ) ) ) ( ( ( ( ( ( is also ) oxygen ) , ) but ) ( in ( groups ( of ( ( three atoms ) ( per molecule ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NN Ozone)) (PRN (-LRB- -LRB-) (NP (QP (CD 0) (CD 3))) (-RRB- -RRB-))) (VP (VP (VBZ is) (ADVP (RB also)) (NP (NN oxygen))) (, ,) (CC but) (VP (PP (IN in) (NP (NP (NNS groups)) (PP (IN of) (NP (NP (CD three) (NNS atoms)) (PP (IN per) (NP (NN molecule))))))))) (. .)))
Ozone (0 3 ) is also oxygen,  but in groups of three atoms per molecule.
(ROOT (S (NP (CD Three) (NN oxygen) (NNS ions)) (VP (VBP make) (PRT (RP up)) (NP (DT an) (NN ozone) (NN molecule))) (. .)))