Since Dmitri Mendeleev’s creation of the Periodic Table in 1869, there have been a few minor changes to its arrangement. As more and more has been learned about the structure of the atom, more refinement has been needed for the periodic table. After the discovery of protons, Henry Moseley proposed a change in the periodic table to reflect the information that Dmitri Mendeleev could not possibly have known about. The periodic table is now arranged in order of atomic number and this means that it is arranged by the number of protons in an atom.
The periodic table still undergoes change. As new elements are discovered, they are added to the table. One of the most recent additions was the element copernicum. This element was named after Nicolaus Copernicus. Copernicus was the scientist responsible for the thought that our Solar System was heliocentric. He thought that that the Sun was the center of the Solar System and other planets revolved around the Sun. Like Mendeleev, Copernicus was not completely correct in his views. Eventually, another astronomer named Johannes Kepler corrected Copernicus when he devised the Laws of Planetary Motion.