The Beginnings of the Periodic Table
Before written history, people were aware of some of the elements in the periodic table. Elements such as gold (Au), silver (Ag), copper (Cu), lead (Pb), tin (Sn), and mercury (Hg).It wasn't until 1649, however, until the first element was discovered through scientific inquiry by HennigBrand . That element was phosphorous (P).
By 1869, 63 elements had been discovered.
The Fathers of the Periodic Table
Lothar Meyer and Dmitri Ivanovich Mendeleev independently produced remarkably similar versions of the periodic table of elements at the essentially the same time.Meyer's 1864 textbook included an abbreviated version of a periodic table used to classify about half of the known elements. In 1868, Meyer constructed an extended table which he gave to a colleague for evaluation. This table unfortunately was not published until 1870, a year after Mendeleev's table was published.
Mendeleev periodic table appeared in his work "On the Relationship of the Properties of the Elements to their Atomic Weights" in 1869. Mendeleev placed many elements out of order based on their accepted atomic weights at the time.
Mendeleev predicted the existence and properties of unknown elements which he called eka-aluminum, eka-boron, and eka-silicon. The elements gallium, scandium and germanium were found later to fit his predictions quite well.
The Modern Periodic Table
Glenn Seaborg discovered the transuranium elements, atomic numbers 94 to 102. The completion of the actinide series allow Seaborg to redesign the periodic table into it current form. Both the lanthanide and actinide series of elements were placed under the rest of the periodic table. These elements technically should be placed between the alkaline earth metals and the transition metals, however, since this would make the periodic table too wide, they were placed below the rest of the elements.Dr. Seaborg and his colleagues are also responsible for the identification of more than 100 isotopes of elements.