19. •Reasons for the classification of elements
•Dobereiner’s Triad
•Newlan’ds law of octaves
•Mendeleev’s periodic table
•Atomic number as the basis for Modern Periodic table
•The Modern Periodic table
•Types of elements
•Merits of The Modern Periodic table
•Defects of The Modern Periodic table
•General trends in The Modern Periodic table
•Alkali metals
•Alkaline earth metals
•Uses of the periodic table