Chemistry
How VSEPR Theory Predicts Molecular Geometry Beyond Ideal Shapes
Quick fact
VSEPR theory predicts that lone electron pairs compress bond angles more than bonding pairs, so the H–O–H angle in water is 104.5° rather than the ideal tetrahedral angle of 109.5°.
Why this is interesting
You know methane is tetrahedral, but why is water bent instead of linear, and why is the H–O–H angle 104.5° instead of 109.5°?