Hybridization in ammonia

We find a similar form of sp hybridization in ammonia. The nitrogen atom has the electronic configuration ls 2s 2p 2p, 2p, and there are now five electrons to be accommodated in the four hybrid orbitals. Thus, one hybrid orbital must contain two electrons from the nitrogen atom with their spins paired. These are known as a non-bonding pair or... 

Figure 1.4 shows sp hybridization in ammonia. In this case one of the sp orbitals has a pair of electrons, so only three sigma bonds can be formed. The structure affects the sigma bond length (0.96 A in ammonia, compared to 1.01 A in methane) and the bond angle (107° vs 109°). This in turn affects the energy of dissociation of the sigma bond 103... 

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