This section covers the application of language model architectures to chemistry. Most notes here focus on models that treat molecular strings (SMILES, IUPAC names, InChI) as sequences, including encoder-only transformers like ChemBERTa and sequence-to-sequence models like ChemFormer and STOUT for structure-to-name translation. A growing set of notes also covers multimodal approaches: models like ChemVLM and InstructMol that connect 2D molecular images or graphs with natural language, enabling tasks like captioning, question answering, and structure retrieval.