Question

What is the vsepr model for $$N{H}_3$$?

Answer 1

Hint :We know that Valence shell electron pair repulsion theory, or VSEPR theory, is a concept used in chemistry to determine the structure of single molecules from the number of pairs of electrons surrounding their central atoms.

Complete Step By Step Answer:
Valence-shell electron pair repulsion theory: The Valence Shell Electron Pair Repulsion Theory abbreviated as VSEPR theory is based on the premise that there is a repulsion between the pairs of valence electrons in all atoms, and the atoms will always tend to arrange themselves in a manner in which this electron pair repulsion is minimalized. This arrangement of the atom determines the geometry of the resulting molecule. In a molecule two types of electron pair are there, bond pair and lone pair.
Ammonia is made up of one atom of nitrogen and three atoms of hydrogen. Nitrogen has eight electrons around it i.e. it has four electron pairs. These pairs are arranged tetrahedral. Of the four pairs: one pair is a lone pair. So, the resulting shape is a trigonal pyramid.

Additional Information:
The repulsion between electron pairs follows the order, lone pair $$$$ lone pair $$>$$ lone pair $$$$ bond pair $$>$$ bond pair $$$$ bond pair, because different types of repulsion distortion in geometry will be observed from the standard geometry w.r.t hybridization.

Note :
Remember that The VSEPR theory assumes that each atom in a molecule will achieve a geometry that minimizes the repulsion between electrons in the valence shell of that atom. The structure of ammonia molecules as per the valence-shell electron pair repulsion theory is trigonal pyramid.