1
The principle
The valence pairs of the central atom, bonding or lone, repel each other and sit as far apart as possible. You count directions: a single, double or triple bond is one direction; so is a lone pair.
High school10 min
Molecular geometry: the VSEPR method
Go from the Lewis structure to the three-dimensional shape: count the directions around the central atom, name the geometry, give the angle and conclude on polarity.
The essentials
2
AXE notation and the base angles
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3
Arrangement of pairs and shape of the molecule
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4
A lone pair repels more
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5
From shape to polarity
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