ABSTRACT
The progress toward the understanding of the building blocks of matter has a long and interesting history. The development of atomic theory from philosophical atomism to a modern understanding is presented. In this chapter, some of the old and even ancient concepts of the limits of divisibility of matter are discussed, along with the rapid development of atomic understanding in the 19th century and early 20th century. The development of the periodic table from a nascent structure with Mendeleev to the form as we know it today is also presented, to give readers a deeper appreciation for the periodic table and the information encoded within it. Foundational concepts such as the conservation of matter, integer ratios of atoms in compounds, and the mole as a scaling factor between the atomic and the macroscopic realms, are considered. The chapter concludes with a presentation of atomic symbology: atomic number (Z), mass number (A), charge number (z), and atomic symbols.
