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$$\text{Boiling Point Peak: } \text{H}_2\text{O}, \quad \text{HF}, \quad \text{NH}_3$$
Concept: The first elements of Groups 15, 16, and 17 display unexpectedly high boiling points relative to the heavier elements in their respective groups due to strong intermolecular hydrogen bonding networks.
Notation:
- $$\text{H}_2\text{O}$$ exists as a liquid at room temperature due to extensive hydrogen bonding, unlike the gaseous $$\text{H}_2\text{S}$$
