Atomic physics although they could be described and classified by their properties (in bulk). The invention of the periodic system of elements by Mendeleev was another great step forward. The true beginning of atomic physics is marked by the discovery of spectral lines and attempts to describe the phenomenon, most notably by Joseph von Fraunhofer. The study of these lines led to the Bohr atom model and to the birth of quantum mechanics. In seeking to explain atomic spectra an entirely new mathematical model of matter was revealed. As far as atoms and their electron shells were concerned, not only did this
Particle volumes, shapes, structures, etc. Examples of macroscopic particles would include powder, dust, sand, pieces of debris during a car accident, or even objects as big as the stars of a galaxy. Another type, "microscopic particles" usually refers to particles of sizes ranging from atoms to molecules, such as carbon dioxide, nanoparticles, and colloidal particles. These particles are studied in chemistry, as well as atomic and molecular physics. The smallest of particles are the "subatomic particles", which refer to particles smaller than atoms. These would include particles such as the constituents of atoms – protons, neutrons, and electrons – as well