The ozone layer

The ozone is a layer of the earth’s atmosphere, the stratosphere, where the highest concentration of ozone ,O3 , is found. It is situated at approximately 10 km to 50 km above the surface of the earth. The Ozone only makes up 0.00006% of the atmosphere. The ozone layer was discovered in 1913 by two french phycisists: Charles Farbry and henry buisson.

This diagram shows the concentrations of ozone measured by the nimbus-7 satellite.
(Author: NASA. Website:http://en.wikipedia.org/wiki/File:Nimbus_ozone_Brewer-Dobson_circulation.jpg)

More about Ozone :
Ozone found at the lower atmosphere acts as a harmful substance. Besides being an air pollutnat, Ozone also causes breathing problems to various animals and burns sensitive plants. Ozone which is found at the upper part of the atmosphere, the ozone layer is beneficial as it prevents ultraviolet rays from reaching the surface of the earth.

Diagram of an ozone molecule.
http://en.wikipedia.org/wiki/File:Ozone-CRC-MW-3D-balls.png

The ozone molecule is made up of three oxygen molecules joined together by weak van der waals forces. it is a powerful oxidizing agent, more powerful than O2.

It can react wiith most metals (excpetions: Gold, Platinum, Silver etc.) into oxides of the metals. For example: 2 Cu+ + 2 H3O+ + O3 → 2 Cu2+ + 3 H2O + O2

Ozone can also react with Nitrogen and Carbon compounds. For example, Ozone can oxidise Nitric Oxide into Nitrogen Dioxide: NO + O3 → NO2 + O2 .

Also, reaction of Ozone with Sulfur compounds into sulfates is also possible. For example, lead (II) Sulfide is oxidised to Lead (II) Sulfate: PbS + 4 O3 → PbSO4 + 4 O2.

Formation of the Ozone Layer:

Ultraviolet rays hit the oxygen molecules in the atmosphere, causing the diatomic oxygen molecules to break into two.
O2 ------ultraviolet rays-----> 2O

Then each individual oxygen atom (aka atomic oxygen) combines with unbroken oxygen molecues to form triatomic molecues known as ozone.
O + O2-----------------------> O3

The Ozone-Oxygen Cycle:

This diagram illustrates the ozone-oxygen cycle.
Created by: NASA derivative work Website found: http://en.wikipedia.org/wiki/File:Ozone_cycle.svg

The Ozone-Oxygen Cycle complements the formation of the ozone layer. It shows how oxygen molecules, which make up about 21% of the atmospheric gases, is being transformed from Oxygen molecules, then into Oxygen atoms and then joined back to form the Ozone molecules and then broken apart again into Oxygen molecules and the cycle repeats itself.