|Molar mass||47.98 g mol-1|
|Appearance||Pale, blue gas|
|Density||0.002144 g cm-3 (at 0 °C)|
-192 °C, 81 K, -314 °F
-112 °C, 161 K, -170 °F
|Solubility in water||1.05 g dm-3 (at 0 °C)|
|Refractive index (nD)||1.2226 (liquid)|
|Hybridisation||sp2 for O1|
|Dipole moment||0.53 D|
|Std enthalpy of
|142.67 kJ mol−1|
|238.92 J K−1 mol−1|
|Related compounds||Sulfur dioxide
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)|
Ozone is a chemical with the symbol O3. This means one molecule of ozone is made of 3 oxygen atoms. Ozone is also called trioxygen. Ozone is formed from dioxygen by the action of ultraviolet light and also atmospheric electrical discharges. It is present in low concentrations throughout the Earth's atmosphere. In total, ozone makes up only 0.6 ppm of the atmosphere.
Ozone is important to planet Earth. There is a portion of the stratosphere with a high concentration of ozone, called the ozone layer. The ozone layer filters out damaging ultraviolet radiation from the Sun, like a kind of sun screen. Without this ozone layer things would not have been able to live on the surface of our planet.
However, ozone is toxic to animals and plants above concentrations of about 0.1 ppm. In humans, it can cause nasal and throat irritation, and nausea. Extended exposure can cause lung oedema. 0.100 ppm is the maximum allowable limit for industrial, public, or occupied spaces in England, Japan, France, the Netherlands and Germany. The Ozone layer is in the 10 to 50 kilometer range of the Earth's atmosphere.