In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Importantly , both classical ( haloperidol ) and atypical ( olanzapine , clozapine and aripiprazole ) antipsychotics were effective in all these models of hyperactivity .
### Output Text:
Importantly , both classical ( <span class="chemical">haloperidol</span> ) and atypical ( <span class="chemical">olanzapine</span> , <span class="chemical">clozapine</span> and <span class="chemical">aripiprazole</span> ) antipsychotics were effective in all these models of hyperactivity . 