All electron pair in ammonia are Oriented in  ----- Geometry 

No. of electron pairs on Central atom =   $\frac{1}{2}(\mathrm{V}+\mathrm{M}-\mathrm{C}+\mathrm{A})$

V=group no. of central atom(valence electrons)

M=No. of monovalent groups(H,X) attached to central atom

C=cationic charge

A=Anionic charge

NH₃ :  

             Group no. of 'N' (valence e^-) = 5

                                     M = 3

$\mathrm{Electron} \mathrm{pairs}=\frac{1}{2}(5+3-0+0)=4$

According to VSEPR theory four electron pairs must be oriented tetrahedrally

to minimise repulsions

No. of atoms directly attached to Central atom = Bond pairs = 3

EP=4

BP=3

lone pairs(LP)=4-3 = 1

Thus the structure of NH₃ molecule is    Trigonal pyramidal

Orientation of all electron pairs = Tetrahedral

Shape of the molecule = Pyramidal (or) Trigonal pyramidal