Around 1869, a Russian chemist, Dmitri Mendeleev, and a German chemist, Julius Lothar Meyer, noticed that if the known (about 65) elements were placed in order of atomic mass, then the properties of the elements appeared to recur in a regular pattern.  Mendeleev was the first to publish his research and arrangement of the elements and is credited with creating the first modern day periodic table.  The Periodic Table of Elements is one of the most important chemistry references.  It arranges all the known elements in a table from top to bottom and left to right in order of increasing atomic number.  So let’s look at some of the patterns and information that the Periodic Table of Elements has to offer.

Source: http://www.chemicool.com/