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: Ages ranged from 4 months to 17 years ; 58 patients were males and 42 females .
### Output Text:
Ages ranged from 4 months to 17 years ; 58 patients were males and 42 females . 