Molecular Shapes Lab
Electron pairs around an atom push each other as far apart as possible. Add bonds and lone pairs, then spin the molecule to see the shape they make.
VSEPR in one sentence
Valence Shell Electron Pair Repulsion: the bonding pairs and lone pairs around the central atom repel each other, so they spread out to be as far apart as possible. Count the electron domains (each bond counts once, even a double bond, and each lone pair counts once) to get the electron geometry.
Why lone pairs matter
Lone pairs sit closer to the central atom and spread out more, so they push harder: lone pair–lone pair > lone pair–bond pair > bond pair–bond pair. That is why water is bent at 104.5° rather than 109.5°. The shape of a molecule names only where the atoms are; lone pairs are invisible in the name but they still decide it.
Yellow arcs show a bond angle. Pale balloons are lone pairs.