There are 118 known chemical elements in the periodic table. Dmitri Mendeleev’s pioneering periodic chart, published in 1869, listed 63 known elements at the time. Following that, scientists found radioactive materials like radon, polonium, and radium. These discoveries extended the periodic table beyond Mendeleev’s original 63 elements. Laboratory synthesis of elements other than uranium expanded the periodic table even further. The discovery and confirmation of new elements, particularly superheavy elements 113 (nihonium) to 118 (oganesson), are the most recent developments.