Ozone (O₃) is a molecule composed of three oxygen atoms. It's a pale blue gas with a pungent odor, and it's significantly different chemically from the diatomic oxygen (O₂) we breathe.
Ozone Formation and Properties
Ozone is formed naturally in the stratosphere through a process driven by ultraviolet (UV) radiation from the sun. This UV radiation breaks apart diatomic oxygen molecules (O₂), creating highly reactive oxygen atoms (O). These single oxygen atoms then combine with other oxygen molecules to form ozone (O₃). This is a continuous cycle, crucial for absorbing harmful UV radiation.
- Formula: O₃
- State: Gas (at room temperature)
- Color: Pale blue
- Odor: Pungent, sharp
- Boiling Point: -112℃
- Formation: Primarily from UV radiation acting on atmospheric oxygen.
Ozone's Role in the Atmosphere
The ozone layer in the stratosphere acts as a critical shield, absorbing most of the sun's harmful UV-B radiation, protecting life on Earth. Ozone in the lower atmosphere (tropospheric ozone) is a pollutant, formed through reactions involving sunlight, nitrogen oxides, and volatile organic compounds. This ground-level ozone contributes to smog and respiratory problems.
- Stratospheric Ozone: Protective, absorbs UV radiation.
- Tropospheric Ozone: Pollutant, contributes to smog and health issues.
Chemical Reactivity
Ozone is a highly reactive molecule, acting as a powerful oxidizing agent. This reactivity is responsible for both its beneficial effects in the stratosphere and its harmful effects in the troposphere. Its strong oxidizing ability allows it to break down pollutants in the atmosphere, yet that same strength can damage lung tissue.
The reference states that ozone is "an elemental molecule with formula O3. An explosive, pale blue gas (b.p. -112℃) that has a characteristic, pungent odour, it is continuously produced in the upper atmosphere by the action of solar ultraviolet radiation on atmospheric oxygen." This highlights its elemental nature, physical properties, and the key role of UV radiation in its formation.
