AP BIOLOGY

Detailed explanation-1: -Chemical identity is the concept that each chemical or substance has a distinct property that separates it from other chemicals. This concept is one of the core foundations of modern chemistry, and is widely used by scientists to classify different substances and understand how they are different from one another.

Detailed explanation-2: -A chemical reaction whose products are chemically identical with the reactants, for example the bimolecular self exchange reaction of CH3I with I-. See also degenerate rearrangement.

Detailed explanation-3: -chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

Detailed explanation-4: -An atom is the smallest unit of matter that still has all of the properties of its element, whereas a molecule is a structure that contains multiple atoms bonded together. The word atom comes from the Greek, atomos, which means indivisible. Thus, atoms cannot be broken down further, whereas molecules can.