H2O molecule. Intensity is proportional to ∫ |Ψ(r)|2dz.
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H2O molecule structure

Isolated O atom has 6 electrons in 4 orbitals
2s ↑↓     2px ↑↓     2py ↑     2pz ↑
After hybridization we get
sp 3↑↓     sp 3↑↓     sp 3↑     sp 3
Two last electrons make bonds with two H atoms. Hybridized orbitals are also used to hold non-bonding (lone pair painted in blue) electrons.
Valence bond theory     updated 9 Apr 2012