Question

O Nici Explain bonding in terms of Valence bond the ory from the picture.. Show a tomic orbitals on Natoms Describe any electron promotion and hybridization necessary land show orbitals involved in both sigma and pi bonding as well as orbital holding lone

Answer 1

Valence bond theory assumes that all bonds are localized bonds formed between two atoms by the donation of an electron from each atom.

The nitrogen atom has 5 valence electrons, two of them in a 2s orbital and the remaining 3 in 2p orbitals, one in each of the three orbitals, p_x, p_y and p_z. In this case, nitrogen is forming a double bond with oxygen, which involves one sigma and one pi bond, one single bond with Cl, and has one lone pair of electrons. This means that nitrogen is hybridized in the molecule, with an sp² hybridization, since it needs three "arms" to either bond or to hold the lone pair.

For this, the two 2s electrons and two of the 2p electrons are promoted to the sp² hybrid orbitals, where two of them are left as lone pairs and the remaining two participate in the sigma bonds with O and Cl:

Osp2-Nsp? G:Nspa-Clp el

The remaining electron stays in the non-hybrid p orbital and forms the pi orbital with oxygen which completes the double bond:

Tt:Op-Np

(pictures are from a Paerson editorial book).