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.
A chemical compound is a chemical that is composed of at least two different types of elements. These elements are combined together in fixed proportions and structures to produce a single type of unique particle. Like an element, a compound is considered a pure substance (meaning there is only one type of particle in the substance).