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 element or element is a chemical substance consisting of atoms having the same number of protons in their atomic nuclei (i.e. the same atomic number, Z).s a special case, the three naturally occurring isotopes of the element hydrogen are often specified as H for 1 H (protium), D for 2 H (deuterium), and T for 3 H (tritium). This convention is easier to use in chemical equations, replacing the need to write out the mass number for each atom.