1. Ozone Distribution in the Atmosphere
STRATOSPHERE
TROPOSPHERE 80 60 20 40 km 50
100
150
Ozone Partial Pressure (b)
MESOSPHERE *

2. OZONE
Structure of Ozone, O3 O O
IN the Stratosphere this allotrope of oxygen, ozone
Protects the earth from the sun’s harmful UV radiation.
It absorbs it.
Can you draw the Lewis Dot Diagram for
Ozone?

3. The Chapman Mechanism + + In the Stratosphere oxygen
exists as O2 and O3 and
separate single oxygen atom, O.
All as it absorbs UV radiation (see left)
These 3 forms are in equilibrium
with each other O O O O

4. Ozone, O2 and the Oxygen Atom in Equilibrium
1) Oxygen is homolytically spilt 
into free radicals.
2) Ozone gas is the  created.
3) UltraViolet rays as  shown in the picture to the right.

5. UV light splits Freon into a free radical of Cl● and CF2Cl ● (freon)
Freon was thought to be inert
CF2Cl2 → CF2Cl. + Cl .
(freon)
UV light splits Freon
into a free radical
of Cl● and CF2Cl ●

6. Ozone Depletion Mechanism
Cl· + O3 → ClO· + O2 ClO· + O3 → Cl· + 2 O2
_____________________
2O3  3 O2

7. Measurements of Ozone and Reactive Chlorine
300
250
200
150
100
500
1.5
0.5
1.0
Reactive Chlorine Abundance (Parts per Billion)
Ozone Abundance (Parts per Billion)
THIS FLIGHT WAS THE “SMOKING GUN” *

8. Fuse School Ozone Destruction #1

9. Fuse School Ozone Destruction #2

10. GREENHOUSE EFFECT V OZONE LOSS
STUDENTS OFTEN CONFUSE THE GREENHOUSE
EFFECT
WITH OZONE DEPLETION.
THEY ARE VERY DIFFERENT. NEXT IS A FILM CLIP
(IF NEEDED ON THE GREENHOUSE EFFECT)

11. Greenhouse Effect

12. BAD OZONE At Ground Level Ozone is toxic When inhaled, ozone can:
cause acute respiratory problems
aggravate asthma
cause inflammation of lung tissue
lead to emergency room visits
impair the body's immune system 

13. Naming halogenoalkanes
A prefix is added to the name of the alkane.
iodine
bromine
chlorine
fluorine
halogen
prefix
five
four
three
two
one
prefix
no. halogen atoms
fluoro- –
chloro-
di-
bromo-
tri-
iodo-
tetra-
penta-
Another prefix is used to indicate how many atoms of each halogen is present.
Numbers are used, where necessary, to indicate to which carbon atom(s) each halogen is attached.

14. As always, keep the numbers as low as possible.
10.1 Naming Alkyl Halides
Name is based on longest carbon chain
Note: It MUST contain the double or triple bond if present)
As always, keep the numbers as low as possible.
Halogens have same priority as alkyl groups

15. Naming with Multiple Halides
If more than one of the same kind of halogen is present, use prefix di, tri, tetra
If there are several different substituents (halogens or alkyls), number them and list them in alphabetical order

16. Naming with Multiple Halides
If more than one of the same kind of halogen is present, use prefix di, tri, tetra
If there are several different substituents (halogens or alkyls) List them in alphabetical order, and keep #’s as low as possible.

21. What are halogenoalkanes?
Halogenoalkanes alkanes with one or more of the hydrogen atoms replaced by a halogen.
trichloromethane
They can contain more than one type of halogen. For example, CFCs (chlorofluorocarbons) ]
Teacher notes
Halogenoalkanes are sometimes called haloalkanes.

22. Physical Properties
Alkyl halides are weak polar molecules. No H-bonds

23. B) propellants for aerosols C) anesthetic
USES of Haloalkanes
Uses of CFCs
CFCs are non-flammable and not very toxic. They therefore had a large number of uses as
A) refrigerants
B) propellants for aerosols
C) anesthetic

24. USES OF ALKYL HALIDES, OR
HALOALKANES

25. PHYSICAL PROPERTIES
Boiling point Increases with molecular size due to increased intermolecular forces
bp / °C
chloroethane 13
1- chloropropane 47
1-bromopropane (Br has 35 e- to 17)
Greater branching = lower inter-molecular forces
1-bromobutane CH3CH2CH2CH2Br
2-bromobutane CH3CH2CHBrCH
2-bromo -2-methylpropane (CH3)3CBr WHY is this lower?
Solubility Haloalkanes are soluble in organic solvents but insoluble in water

26. Why Branching has lower Boiling Point
Branched alkanes have weaker forces because of the smaller area of contact between the molecules.
Less energy is needed to overcome the intermolecular force. Linear alkanes can line up more closer and therefore have stronger forces