Chemistry is the study of matter (the substances that make up our world). A more detailed description of chemistry is :
"...A basic science whose central concerns are
(1) the structure and behavior of atoms (elements);
(2) the composition and properties of compounds;
(3) the reactions between substances, with their accompanying energy exchange; and
(4) the laws that unite these phenomena into a comprehensive system.
Chemistry evolved from the medieval practice of alchemy. Its bases were laid by the scientists Boyle, Lavoisier, Priestly, Berzelius, Avogadro, Dalton, and Pasteur...."
From "Chemistry." Hawley's Condensed Chemical Dictionary. Hoboken: Wiley, 2007.Credo Reference.
Chemical elements are displayed in a periodic table arranged by atomic number:
"Periodic Table." Philip's Encyclopedia. London: Philip's, 2008. Credo Reference.