The shapes of molecules with four charge centres

Water H2O
Ammonia NH3
Methane CH4
The water molecule has two bonding pairs and two lone pairs. All four pairs arrange in a tetrahedral orientation but as we cannot see the two lone pairs then we see the molecule as angular or bent. The extra repulsion of the two lone pairs distorts the usual tetrahedral bond angle of 109,5º and instead there is a bond angle of 104º
The Ammonia molecule has three bonding pairs and one lone pair. All four pairs arrange in a tetrahedral orientation but as we cannot see the lone pair then we see the molecule as pyramidal. The extra repulsion of the lone pair for the bonding pairs distorts the usual tetrahedral bond angle of 109,5º and instead there is a bond angle of 107º
The Methane molecule has four bonding pairs and no lone pairs. All four pairs arrange in a tetrahedral orientation and the molecule is a perfect tetrahedral shape. The bond angle is 109,5º the same as would be theoretically expected