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: CASE SUMMARY : A 69 - year - old white female presented to the emergency department with a history of confusion and paranoia over the past several days .
### Output Text:
CASE SUMMARY : A 69 - year - old white female presented to the emergency department with a history of confusion and paranoia over the past several days . 