o3 is heavier than air, then also, it is at the top of all layers. why??

Answer 1

In principle, the density of a gas is proportional to its molecular mass (in air, MM of N2 is 28 g/mol; O2 is 32; Ar is 40; O3 is 48), so that you would be right, because ozone exhibits the greatest density. However, some more factors affect the mixing of gases, such as diffusion coefficient and viscosity, and prevent instantaneous uniform mixing.
Not a minor aspect of the matter rests on the fact that the following dynamic equilibrium occurs at that high altitude:
O2 + O = O3 due to UV radiation, so that any single O3 molecule is unstable.
Different is the situation when O3 is a pollutant at the ground level (produced mainly by engines) - it's particularly persistent because it's HEAVY. And then you are right!

To Smilam: I didn't say that ozone floats up; on the contrary, I tried to explain why ozone doesn't sink, in accordance with the true spirit of the question.

Answer 2

O3 is not heavier than air. O3 is not in the top of all layers, it is present in the 2nd layer that is stratosphere. It prevents harmful UV radiations of sun from reaching the earth.

Answer 3

Ozone (O3) is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic species O2. Ground-level ozone is an air pollutant with harmful effects on the respiratory systems of animals. On the other hand, ozone in the upper atmosphere protects living organisms by preventing damaging ultraviolet light from reaching the Earth's surface. It is present in low concentrations throughout the Earth's atmosphere. It has many industrial and consumer applications. Ozone therapy is a controversial alternative medicine practice; mainstream scientific medicine has found ozone to be harmful to humans, and equipment intended to be used for ozone therapy is banned in the United States.
Ozone, the first allotrope of a chemical element to be described by science, was discovered by Christian Friedrich Schönbein in 1840, who named it after the Greek word for smell (ozein), from the peculiar odor in lightning storms. The odor from a lightning strike is from ions produced during the rapid chemical changes, not the ozone itself.

Answer 4

That Len guy is right, but I think he doesn't speak english very well.
Basically ozone doesn't float up to the top layer, it gets created when light from the sun hits oxygen gas that is in the top layer and it turns the oxygen into ozone. It also turns the ozone back into oxygen and it's that process that blocks out the UV rays.

Answer 5

"Air" is 78% Nitrogen, 21% Oxygen, and 1% 'other'. Ozone is not "heavier" than "air". Its also not found only in the ozone layer. It is also a near atmosphere pollutant.

http://en.wikipedia.org/wiki/Ozone

Answer 6

O3 is formed photochemically in the upper atmosphere.

Answer 7

Len might not have articulated his answer in the plainest possible language, but he is correct.