Chemistry and Chemical Disasters. Chemical combination of two or more atoms of the same chemical element (such as O2 - which is Oxygen) or different chemical elements (such as H2O - which is water)
The Association of Petrochemicals Producers in Europe (APPE), The European petrochemical industry, Glossary of Terms on Chemical Safety for Use in IPCS Publications, van Nieuwenhuyse, Brussels 2006. http://www.petrochemistry.eu/glossary.html, (Petrochem Ind - Brit) {473}