( We ( ( ( have already ) ( ( ( ( seen ( constiturtional isomers ) ) ( -LRB- ( ( which ( have ( atoms ( bonded ( to ( ( different atoms ) ( such ( as ( ( butane and ) isobutane ) ) ) ) ) ) ) ) ) -RRB- ) ) ) and ) ( ( ( ( geometric isomers ) ( -LRB- ( also ( stereoisomers -RRB- ) ) ) ) ( like ( ( E and ) Z ) ) ) ( in alkenes ) ) ) ) . ) )
(ROOT (S (NP (PRP We)) (VP (VBP have) (ADVP (RB already)) (VP (VP (VBN seen) (NP (JJ constiturtional) (NNS isomers))) (PRN (-LRB- -LRB-) (SBAR (WHNP (WDT which)) (S (VP (VBP have) (NP (NP (NNS atoms)) (VP (VBN bonded) (PP (TO to) (NP (NP (JJ different) (NNS atoms)) (PP (JJ such) (IN as) (NP (NN butane) (CC and) (NN isobutane)))))))))) (-RRB- -RRB-)) (CC and) (VP (ADJP (ADJP (ADJP (RB geometric) (JJ isomers)) (PRN (-LRB- -LRB-) (ADVP (RB also)) (ADJP (JJ stereoisomers)) (-RRB- -RRB-))) (PP (IN like) (NP (NNP E) (CC and) (NNP Z)))) (PP (IN in) (NP (NNS alkenes)))))) (. .)))
We have already seen constiturtional isomers (which have atoms bonded to different atoms such as butane and isobutane) and geometric isomers (also stereoisomers) like E and Z in alkenes.
(ROOT (S (NP (NP (NNS Alkenes)) (PP (IN with) (NP (NP (DT the) (JJ same) (NNS atoms)) (PP (CC but) (NP (JJ different) (NNS shapes)))))) (VP (VBP are) (VP (VBN called) (NP (NNS isomers)))) (. .)))