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In this example, NO2, the Lewis diagram shows nitrogen
at the center with one lone electron. The nitrogen and and one
oxygen are bonded through a double bond which counts as "one
electron pair". Hence the molecule has three electron pairs
and is trigonal planar for electron pair geometry.
The one lone electron exerts a less repulsion than normal
on the two bonding oxygen atoms so they are able to spread out
more to a 134obond angle from the ideal of 120o
The Lewis diagram is as follows:
N = 5 e-
O = 6e- x 2 = 12e-
Total electrons = 17
All oxygen atoms have an octet of electrons. Nitrogen atom
does not have an octet because the whole molecule is short an
electron. This electron deficient feature of the molecule make
is very reactive because it will try to react with some other
molecule to complete the octet.
Nitrogen dioxide is a main component of photochemical smog
air pollution. It is coproduced from the high temperature combustion
of gasoline in the presence of air which also contains nitrogen.