Intermediate Topic 654 of 1102 Inorganic Chemistry
Ozone
O3 is a triatomic oxygen allotrope that shields Earth from UV in the stratosphere.
In-depth explanation of Ozone
Ozone, O3, is a bent, pale blue triatomic allotrope of oxygen with strong oxidizing power. It forms from O2 when ultraviolet light or an electric discharge splits oxygen molecules. In the stratosphere, ozone absorbs most of the harmful UV-B and UV-C radiation, shielding life on Earth. Ground-level ozone is a pollutant that damages lungs and plants. Chlorofluorocarbons release chlorine atoms in the stratosphere, and these destroy ozone in catalytic cycles, creating the Antarctic ozone hole. The Montreal Protocol phased out these ozone-depleting substances.
Going deeper: Ozone
Key ideas: O3 is bent with bond angle 117 degrees, diamagnetic, blue gas, with an O-O bond order of 1.5 via resonance. Made by silent electric discharge through O2: 3O2 gives 2O3, delta H = +285 kJ per mol (endothermic). Strong oxidant: PbS to PbSO4, I- to I2 (used as test, with starch). Stratospheric ozone absorbs UV between 200 and 315 nm. Chlorine radicals catalyze depletion: Cl + O3 gives ClO + O2.
Common mistakes and connections: Students confuse stratospheric protective ozone and tropospheric ozone, a smog pollutant. One Cl atom can destroy about 100000 ozone molecules because it is regenerated. Ozone is thermodynamically unstable and decomposes to O2. The Montreal Protocol phased out CFCs. Links to free-radical chain reactions, catalysis and resonance.
Visualization of Ozone
Bent O3 molecule: it absorbs UV-B and UV-C in the stratosphere, and chlorine atoms from CFCs catalytically destroy it. The interactive lesson shows this as a live animation or chart.
Worked example and use case
A single chlorine atom from a CFC can destroy many thousands of ozone molecules because it acts as a catalyst.
Frequently asked questions about Ozone
What is Ozone?
O3 is a triatomic oxygen allotrope that shields Earth from UV in the stratosphere.
Is Ozone a beginner, intermediate or advanced topic?
Ozone is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Ozone?
Study these earlier topics in Inorganic Chemistry first: Phosphoric Acid, Fertilizers, Oxygen Family.
What comes after Ozone?
The next topics in Inorganic Chemistry are Oxides and Sulfur Allotropes.
Can I practise Ozone with quizzes?
Yes. The interactive lesson includes a self-check question on Ozone, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Ozone fits in Inorganic Chemistry
Ozone is topic 39 of 113 in Inorganic Chemistry.