January 2026
Intermediate
368 pages
12h 59m
English
Content preview from Pearson IIT Foundation Class 9 Chemistry, 2026
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CHAPTER 5
Periodic Classification of Elements
Key Ideas 
After completing this chapter, you should be able to:
✦ describe earlier versions of classification of elements, like, Newland’s law of octaves and Dobereiner’s Triads with emphasis on Mendeleev’s periodic table.
✦ understand the placement of elements on modern periodic table—its merits and defects.
✦ explain about the similarities and gradual changes in the properties, such as, atomic size, ionization energy, electron affinity, electropositivity, oxidizing, reducing property, etc.
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