1. Group # 7
Group Review Sheet
All members in the group should participate in completing this task.
Due Date: Thursday, April 10, 2014 in Class.
I. Materials being reviewed:
21.3
II. Summarize the main ideas in the materials reviewed in no more than five points. Give a very
brief explanation for each.
1. The formation & the functions of the ozone (O3)layer :
The formation of O3 in the stratosphere (STP) region begins with the photodissociation of oxygen O2 molecules by solar
radiation at wavelength (λ) below 240 nm :
.
The ozone layer in the STP region prevent ultraviolet (UV) radiation emitted by the sun from reaching Earth's surface .
2. The factors effecting the O3 layer :
Fluorocarbon with chlorine compounds (CFCs), Generally known by the trade name Freons, are relatively inert that CFCs
slowly diffuse unchanged up to the stratosphere, where UV radiation of wavelengths between 175 and 220 nm causes them to
decompose . Then, reactive chlorine atoms undergo the following reactions:
& converting O3 & O to O2 .
Another group of compounds are the nitrogen oxides (NOx) which come from the exhausts of aircraft and from human and
natural activities on Earth. They participates in the destruction of O3 almost the same way as CFCs .
3. The effects of the depletion of the O3 layer on Earth :
O3 acts as our protective shield against UV radiation, which can cause global warming, induce skin cancer, weaken the immune
system, cause genetic mutations, and destroy crops and other forms of vegetation. Moreover, UV can cause dangerous effects on
Marine Ecosystems, Biogeochemical Cycles, Materials, etc .
4. Polar O3 holes :
In the stratosphere, a stream of air known as the “polar vortex” circles Antarctica in winter. This condition leads to the
formation of polar stratospheric clouds (PSCs) which convert HCl & ClNO3 to more reactive chlorine molecules:
.
In spring , the sunlight splits molecular chlorine into chlorine atoms,
5. The solutions of reducing the depletion of O3 layer :
There are many possible solutions that can be used to control the depletion of O3 layer like substituting CFCs with HCFC-123 &
some treatment processes .
5 points

2. Group # 7
This table should be completed by the group leader
.
Member’s Name Task Assigned Accomplishment
1
ALMOBUED, SAUD
ABDULRAHMAN
The Formation & The Functions of
The O3 Layer
Accomplished
2
ALSHADDAD, MOHAMMED
ABDULAZIZ
The Factors Effecting the O3 Layer Accomplished
3
ALRASHED, ALI
ABDULLAH
The Effects of the Depletion of the
O3 Layer on Earth
Accomplished
4
ALARBASH, JAFFAR
HASSAN
Polar O3 Holes Accomplished
5
ALSAHAFI, AHMAD
MESHAL
The Solutions of Reducing The
Depletion of O3 Layer
Accomplished