The periodic table, also called as the periodic table of elements, is a classification of elements and atomic types according to their increasing atomic number, as well as chemical and physical properties as well as electron configuration in the outer electron shells. The vertical columns on the periodic table are called groups and horizontal rows on the periodic table are called periods. The elements of periodic table can also be categorized according to element families (groups), state of matter, chemical classification or element block. The block names (s, p, d, f) originated from descriptions of spectroscopic lines of atomic orbitals: sharp, principal, diffuse and fundamental. The first version of the periodic table was presented by Russian chemist Dmitry Mendeleev in February 1869. For quick and simple reference, go to the
list of chemical elements