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# NH3 Molecular Geometry

Some points About Ammonia has been given below:
• Ammonia has four groups of electrons and so it has the same electronic geometry as other molecules like CH4.
• In case of NH3 however, one group has an unshared pair of electrons, and as per VSEPR the four electron groups around a central atom will be directed towards the corners of tetrahedron to give maximum separation.
• N has tetrahedral electronic geometry, which refers to the geometric arrangement of electron groups around central atom.
• The molecular geometry however excludes the lone pairs on the central atom and describes only the arrangement of atoms around the central atom.
• Ammonia (NH3) is an example of molecule in which the central atom has both shared and unshared electron pairs. The shape of ammonia molecule (NH3) is trigonal pyramid.
• There are three bonding pairs of electrons and one non bonding pair. The bond angle in a molecule of ammonia are 107o, a value very close to tetrahedral angle (109o.5').
• We can write a general tetrahedral structure for the electron pairs of ammonia by placing the non bonding pair at one corner.
• A tetrahedral arrangement of the electron pairs explains the trigonal pyramidal arrangement of the four atoms.
• The bond angles are 107o (not 109o.5') because the non bonding pair occupies more space than the bonding pairs.

Molecular geometry is explained by the arrangement of atoms. The nitrogen atom is at the apex of the trigonal pyramidal arrangement and the other three atoms are at the corners of the triangular base of the pyramid.

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## Hybridization of NH3

In order to arrive the molecular shapes, chemist combine the envisioned shapes of individual atoms to form the known shapes of molecules and this concept is called hybridization. It describes the need to modify the atomic orbitals of isolated atoms to conform to the known shapes of molecules.
In NH3 the lone pair of electrons occupies one of the sp3 hybrid orbitals. Each of the other three sp3 orbitals participates in bonding by sharing the electrons with another atom. They overlap with the half-filled H 1s orbital in ammonia.