Hybridization a scheme for tetrahedral and related species

The notation sp means that one and threep atomic orbitals mix to form a set of four hybrid orbitals with different directional properties. 

Worked example 4.1 Hybridization scheme for the nitrogen atom in NH3 

Use VSEPR theory to account for the structure of NH3, and suggest an appropriate hybridization scheme for the N atom. 

The ground state electronic configuration of N is [He]2 2/ . Three of the five valence electrons are used to form three N—H single bonds, leaving one lone pair. 

The structure is trigonal pyramidal, derived from a tetrahedral arrangement of electron pairs  

A similar scheme to those described above can be derived to generate four sp hybrid orbitals from one 2s and three 2p atomic orbitals. The sp hybrid orbitals are described by the normalized wavefunctions in eqs. 5.6-5.9 and are shown pictorially in Fig. 5.6a. Each sp hybrid orbital possesses 25% s character and 75% p character, and the set of four equivalent orbitals defines a tetrahedral framework. 

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