In this chapter, we will discuss the development of the periodic table and the periodic law. The arrangement of elements in the modern periodic table is organized into eight vertical columns (groups) and seven horizontal rows (periods) based on their atomic number.
Based on the electronic configuration, elements can be classified into four types in the periodic table, viz s-block, p-block, f-block, and d-block elements. More than 70-80% of the known elements are metals. Elements located at the top of the periodic table are nonmetals and are less than 20. In a group, as the atomic number increases, the metallic character increases. In a period, there is a decrease in the metallic character from left to right. Also, the chemical, as well as the physical properties, vary with their atomic number. Elements of the same group exhibit similar chemical properties because of the similar valence shell electronic configuration.