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: The patient ' s Glasgow Coma Score was 3 , with normal findings shown on computed tomography scan of the head 72 hours following an episode of cardiac arrest on day 10 .
### Output Text:
The patient ' s Glasgow Coma Score was 3 , with normal findings shown on computed tomography scan of the head 72 hours following an episode of cardiac arrest on day 10 . 