Periodic Classification of Elements

1. Is a potassium atom larger, smaller or the same size as a potassium ion? Explain.
2. Why does the atomic size increase in going down any family of the periodic table?
3. Why do metals form positive ions and non-metals form negative ions?
4. Which of the following pairs would have a larger size and why?
(a) K or K+ (b) F or F
5. Why does the first ionization energy increase from left to right in a given period of the periodic table?
6. Why ionization energy of alkali metals decreases as the atomic number increases?
7. Why do the Oxide O and Sulphide S have negative charge?
8. What is the basis of the classification of elements in Mendeleev’s periodic table?
9. Why do atomic radii decrease across a period and increase in a group with the increase of atomic number?
10. Arrange the elements Na, Li and K in the increasing order of first ionization energy.
11. Why is the ionization energy of Lithium greater than Sodium?
12. Compare the size of F and Na+ with the atomic size of Neon.
13. Why the size of Cl ion is larger than Cl atom where as the size of K+ ion is smaller than that of K atom?
14. State Modern Periodic law.
15. Why ionization energy of oxygen is less than that of nitrogen?
16. What is the basic difference between Modern Periodic Table and Mendeleev’s Periodic Table?

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