how to find bond angle between molecule when lone pair and bonding are known

VSEPR modelor VSEPR theory talks about the shape of a molecule depending upon the number of atoms or ions surrounding the central atom/ion.
According to this theory
“The shape of a given species (molecule or ion) depends on the number and nature of electron pairs surrounding the central atom/ion of the species.”
Molecule Number of lone pair on central atom
Bond angle(and contraction in bond angle)
NH3 1 107.5o(109.5 - 107.5 = 2o)
H2O 2 105.5o(109.5 - 105.5o= 4o)
CH40 109.5o(109.5 - 109.5 = 0)
as can be seen as the no of lone pair increses the bond angle decrease greater the lone pait greater will be the decrese in bond angle


Number of electron pairs
Spatial arrangement/ Geometry/angle
2 Linear- 180
3 Trigonal planar- 120
4 Tetrahedral- 109.5
5 Trigonal bi pyramidal – 120
6 Octahedral – 90, 90
7 Pentagonal bi pyramidal- 72, 90