The periodic table was first developed by Dmitri Mendeleev, a Russian chemist, in 1869. He organized the known chemical elements into a table based on their atomic masses (now replaced by atomic number) and similar chemical properties.
What made Mendeleev’s periodic table revolutionary was that he left gaps for elements that had not yet been discovered and predicted their properties with remarkable accuracy. For example, he predicted the existence and characteristics of elements like gallium and germanium years before they were actually found.
Mendeleev’s periodic table laid the foundation for the modern periodic law, which states that the properties of elements are a periodic function of their atomic numbers. Today, the periodic table is a fundamental tool in chemistry, organizing over 100 elements and providing key information about their atomic structure and behavior.