Compound reference
Water
H₂O
The chemistry
Two lone pairs on oxygen squeeze the H–O–H angle below 109.5°. That bend is why water is a polar liquid that dissolves so much.
Remember it as…
Two bonds, two lone pairs - bent at 104.5°. The angle is the molecule's signature.
Common mix-up
Water is NOT linear like CO₂. The two lone pairs on oxygen push the H–O–H bonds together, and the resulting bend is what makes water polar. A linear H–O–H would be non-polar and life as we know it would not exist.
Where the name comes from
Old English wæter, from Proto-Germanic *watōr - the same root that gave Greek hydōr (whence "hydrate", "hydrogen").
Where you meet it
Liquid at room temperature, expands when frozen, dissolves nearly every ionic compound - all consequences of the bend.
PubChem facts
- IUPAC name
- oxidane
- Molecular weight
- 18.015 g/mol
Also known as: dihydrogen monoxide, dihydrogen oxide
Atomic theoryBondingMolecular geometry
Chemical data from PubChem (NIH/NCBI)