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: Themography confirmed the existence of an excessive breast stimulation in 1 women who complained of moderate mastodynia and in 5 of the 7 women who complained of severe mastodynia .
### Output Text:
Themography confirmed the existence of an excessive breast stimulation in 1 women who complained of moderate mastodynia and in 5 of the 7 women who complained of severe mastodynia . 