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 interictal electroencephalogram ( EEG ) showed a generalized slowing to 5 per second theta rhythms with bilateral generalized high - amplitude discharges .
### Output Text:
The interictal electroencephalogram ( EEG ) showed a generalized slowing to 5 per second theta rhythms with bilateral generalized high - amplitude discharges . 