Free radicals are also important
in many environmentally significant reactions.
For example, photochemical smog, which forms
as a result of the action of sunlight on air pollutants,
is formed in part by the following two steps.
X
NO2 NO � O
O � O2 O3
UV light
� Ozone damages rubber products.
The product of this reaction, ozone, is a pollutant in
the lower atmosphere. Ozone is an eye and lung irritant
and also accelerates the weathering of rubber
products. Write Lewis structures for each of the reactants
and products in the preceding reactions.
To write Lewis structures for each of the reactants and products in the given reactions, we need to understand the concept of Lewis structures and how to determine the arrangement of atoms and electrons.
A Lewis structure is a diagram that represents the arrangement of atoms in a molecule and shows the bonding between them. It is based on the concept that atoms tend to gain, lose, or share electrons to achieve a stable electron configuration, usually with a full outer shell of electrons.
Let's start with the reactants:
1. NO2 (nitrogen dioxide):
The Lewis structure for nitrogen dioxide consists of one nitrogen atom (N) bonded to two oxygen atoms (O). To determine the arrangement of atoms and electrons, we follow the following steps:
- Nitrogen (N) is the least electronegative atom, so it will be the central atom.
- Oxygen (O) is more electronegative than nitrogen, so it will form a double bond with nitrogen.
The Lewis structure for NO2 is:
O
||
N=O
2. O (oxygen):
Oxygen exists as diatomic molecules (O2) and has a stable Lewis structure in which each oxygen atom shares two electrons with the other oxygen atom to form a double bond. Therefore, the Lewis structure for O2 is:
O=O
Now let's move on to the products:
1. NO (nitric oxide):
The Lewis structure for nitric oxide consists of one nitrogen atom (N) bonded to one oxygen atom (O). To determine the arrangement of atoms and electrons, we follow the same steps as before:
- Nitrogen (N) is the central atom.
- Oxygen (O) forms a single bond with nitrogen.
The Lewis structure for NO is:
O
||
N-O
2. O3 (ozone):
Ozone is formed by the combination of three oxygen atoms (O). The Lewis structure for ozone depends on the resonance structures because the oxygen atoms continuously exchange their positions. However, we can represent one of the resonance structures as follows:
O
||
O-O
These Lewis structures represent the reactants and products involved in the given reactions.