MOLECULAR TRANSPORT
SELF STUDY -2
E9A.6(a) Describe the bonding in methylamine, CH3NH2, using hybrid orbitals.
E9A.6(b) Describe the bonding in pyridine, C5H5N, using hybrid orbitals.
Answers:
(a) Considering the Lewis structure of the molecule, the electron-pair geometry around and
nitrogen is attached to the remaining hydrogen.
The nitrogen atoms have three half filled sp3 orbital and one filled with a lone pair and
electronic configuration method shown below.
Complete(spdf) notation of N=7[N]1s22s22p3
↑↓ ↑↓ ↑↑↑
filled one loan pair: ↑↓ ↑ ↑↓↑↑
1s22s22p3 1s22s12p4
The methylamine molecule, the electron-pair geometry around both the C and N atoms in
CH3-NH2 is a tetrahedral. Then we assign sp3 hydridization to each atoms and C-N bond
is formed by trigonal overlap of sp3 orbital on these atoms. Each C-H bond is formed by
overlap of a carbon sp3 orbital with a hydrogen 1s orbital and the N-H bond if formed by
overlapping of oxygen sp3 orbital with hydrogen 1s orbital. The one lone pairs on nitrogen
occupy the remaining sp3 orbital on the atom.
(b) The lone pair in sp2 orbital is perpendicular to the p orbitals and pi bond in the molecule.
The electron pairs from the nitrogen that participates in aromaticity is the one in the C=N
bond.
D9B.2 What feature of molecular orbital theory is responsible for bond formation?
Answer:
In molecular orbital theory atomic orbitals of combining atoms are mixed/overlap with each other
to form new orbitals known as molecular orbitals. That is two atoms come closer to each other
interaction takes place and they form the bond. The energy of combining orbitals should be same.
P9C.2 Before doing a calculation, sketch how the overlap between a 1s orbital and a 2p orbital
directed towards it can be expected to depend on their separation. The overlap integral between
an H1s orbital and an H2p orbital directed towards it on nuclei separated by a distance R is
