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: Minor side effects included nausea ( thirteen patients ) , emesis ( eight of the thirteen patients with nausea ) , clumsiness ( evident as ataxic movements in ten patients ) , and dysphoric reaction ( one patient ) .
### Output Text:
Minor side effects included nausea ( thirteen patients ) , emesis ( eight of the thirteen patients with nausea ) , clumsiness ( evident as ataxic movements in ten patients ) , and dysphoric reaction ( one patient ) . 