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: Three young infants , all of birth weight < 1 , 500 g , experienced myoclonus following the intravenous administration of lorazepam .
### Output Text:
Three young infants , all of birth weight < 1 , 500 g , experienced myoclonus following the intravenous administration of <span class="chemical">lorazepam</span> . 