What's Happening in Erie County. 1  September 1 - September 30 : Agricultural Districts Open Enrollment Period. 2  September 4 : Erie County Government offices are closed today. 3  September 5 : Justice Assistance Grant (JAG) Public Notification - Fiscal Year 2017.
Definition. 1  As a noun, the common definition of chemical is a substance that is produced or used in a process (reaction) involving changes to atoms or molecules. 2  As an adjective, chemical means of or pertaining to chemistry.
The rules for chemical nomenclature are based on the division of substances into different categories. The major division is between organic compounds and inorganic ones. Organic compounds contain carbon, usually in combination with hydrogen, oxygen, nitrogen, or sulfur.