Formation of ozone
How the layer is made.
Making ozone
Oxygen gas, O₂, is found in the atmosphere. Ozone, O₃, is found higher up.
How do you think ozone is made in the upper atmosphere?
What this lesson covers
The idea
In the upper atmosphere, higher-energy UV radiation splits some O2 molecules into free oxygen atoms, which combine with O2 to form ozone: O2 → O + O; O + O2 → O3.
Making ozone
Oxygen gas, O₂, is found in the atmosphere. Ozone, O₃, is found higher up.
How do you think ozone is made in the upper atmosphere?
- UV radiation acts on oxygen molecules
- Plants release it as they grow
- The wind mixes it from the soil
Build ozone
Press Next step.
Two steps
First, higher-energy UV radiation splits some O₂ molecules into free oxygen atoms. Then each free atom joins an O₂ molecule to make O₃, ozone. So ozone at the higher levels of the atmosphere is a product of UV radiation acting on oxygen.
Higher-energy UV radiation splits some O₂ molecules into free oxygen atoms, which combine with O₂ to form ozone: O₂ gives O + O; O + O₂ gives O₃.
Notes
UV splits O₂ to O + O; then O + O₂ gives O₃, ozone.
Check yourself
What splits some O₂ molecules into free oxygen atoms in the upper atmosphere?
When an O₂ molecule is split, how many free oxygen atoms does it give?
Answer: 2
O₂ gives O + O, which is 2 free oxygen atoms.
What does a free oxygen atom, O, combine with to form ozone?
Why is the equation O + O₂ gives O₃ balanced?
- Ozone itself. Ozone is the product that forms at the end. It does not split O₂.
- Chlorofluorocarbons. CFCs have been linked to the decrease of ozone. UV radiation is what splits O₂.
- Higher-energy UV radiation — correct. Yes!
- A molecule of oxygen, O₂ — correct. Yes!
- Another free oxygen atom, O. Two atoms joined make O₂. Ozone has three atoms.
- Nothing, it stays free. The free oxygen atoms combine with molecular oxygen to form ozone.
- There is one oxygen atom on each side. The left has 1 atom in O and 2 atoms in O₂, which is 3 atoms. The right, O₃, has 3 atoms.
- There are three oxygen atoms on the left and three on the right — correct. Yes!
- There are two oxygen atoms on the left and one on the right. The left has 3 atoms and the right has 3 atoms. None are lost.