2.Periodic Classification

Historical Background: The chapter begins by discussing early attempts at classifying elements, such as Johann Döbereiner’s triads and Dmitri Mendeleev’s periodic table. Mendeleev's work is highlighted for its groundbreaking approach to organizing elements by atomic mass and predicting the existence of undiscovered elements.

Modern Periodic Table: Students learn about the modern periodic table, which is arranged by atomic number rather than atomic mass. This arrangement reflects the periodic law, which states that the properties of elements are periodic functions of their atomic numbers.

Periodic Trends: The chapter covers various trends in the periodic table, including atomic radius, ionization energy, electron affinity, and electronegativity. Students will understand how these properties change across periods and down groups.

Classification of Elements: The periodic table is divided into several blocks (s-block, p-block, d-block, and f-block) based on the electron configurations of elements. Students will learn about the characteristics and examples of elements in each block.

Groups and Periods: The chapter details the significance of groups (vertical columns) and periods (horizontal rows) in the periodic table, explaining how elements within the same group share similar chemical properties due to their similar valence electron configurations.

Special Categories: There is a focus on specific categories of elements such as metals, non-metals, and metalloids, and how their properties vary according to their position in the periodic table.