CHAPTER 5 - PERIODIC CLASSIFICATION OF ELEMENTS 1. State the Modern Periodic Law. 2. Write the name of the element having electronic configuration 2,8,3. 3. On what basis has the Modern Periodic Table been formed? 4. Give any one example to show Dobereiner's triad. 5. What are the limitations of Mendeleev's Periodic Table? 6. How are the limitations of Mendeleev's Periodic Table addressed by Modern Periodic Table? 7. How does atomic size vary as we move (a) down a group (b) across a period? 8. The atomic size (in pm) for some elements has been given below. Arrange them in ascending order. Na Li Rb Cs K 186 152 246 262 231 9. How are metalloids different from metals and non-metal? Give two examples of metalloids. 10. Three elements X,Y and Z have electronic configuration as follows: X-2 Y-2,6 Z-2,8,2 (a)Which element belongs to second period?