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: Five children , aged 3 to 11 years , treated with carbamazepine for epilepsy , had an acute aberrant reaction characterized by the onset of myoclonic , atypical absence and / or atonic ( minor motor ) seizures within a few days .
### Output Text:
Five children , aged 3 to 11 years , treated with <span class="chemical">carbamazepine</span> for epilepsy , had an acute aberrant reaction characterized by the onset of myoclonic , atypical absence and / or atonic ( minor motor ) seizures within a few days . 