Ozone

Ozone
IUPAC name	Trioxygen
Identifiers
CAS number	10028-15-6
PubChem	24823
EC number	233-069-2
MeSH	Ozone
ChEBI	CHEBI:25812
RTECS number	RS8225000
SMILES	o:o:o
InChI InChI=1/O3/c1-3-2
Gmelin Reference	1101
Properties
Molecular formula	O3
Molar mass	47.98 g mol-1
Appearance	Pale, blue gas
Density	0.002144 g cm-3 (at 0 °C)
Melting point	-192 °C, 81 K, -314 °F
Boiling point	-112 °C, 161 K, -170 °F
Solubility in water	1.05 g dm-3 (at 0 °C)
Refractive index (nD)	1.2226 (liquid)
Structure
Space group	C2v
Coordination geometry	Digonal
Molecular shape	Dihedral
Hybridisation	sp2 for O1
Dipole moment	0.53 D
Thermochemistry
Std enthalpy of formation ΔfHo298	142.67 kJ mol−1
Standard molar entropy So298	238.92 J K−1 mol−1
Hazards
EU classification	O
NFPA 704	0 4 4 OX
Related compounds
Related compounds	Sulfur dioxide Thiozone
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 makes up only 0.6 parts per million (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.