PERIODIC CLASSIFICATION OF ELEMENTS
1. How many groups and periods are there in the modern periodic table? How do the atomic size and metallic character of elements vary as we move:
(a) down a group and
(b) from left to right in a period (CBSE 2015)
2. How many vertical columns are there in the modern periodic table and what are they called? (CBSE 2013)
3. Given below are some elements of the modern periodic table:
4Be, 9Fe,14Si, 19K, 20Ca
(i)Select the element that has one electron in the outermost shell and write its electronic configuration.
(ii)Select two elements that belong to the same group. Give reason for you answer.
(iii)Select two elements that belong to the same period. Which one of the two has bigger atomic size? (CBSE 2013)
4. Write the number of periods the modern periodic table has. How do the valency and metallic character of elements vary on moving from left to right in a period? How do the valency and atomic size of elements vary down a group? (CBSE 2013)
5. An element �M� has atomic number 12.
6. (a)Write its electronic configuration.
(b)State the group to which �M� belongs.
(c)Is �M� a metal or a non-metal.
(d)Write the formula of its chloride. (CBSE 2012)
7. What physical and chemical properties of elements were used by Mendeleev in creating his Periodic Table? List two observations which posed a challenge to Mendeleev�s Periodic Law. (CBSE 2008 F)
8. State any two limitations to Mendeleev�s classification.
How does electronic configuration of atoms change in period with increase in atomic number?
9. (i) How do you calculate the possible valency of an element from the electronic configuration of its atoms?
(ii) Calculate the valency of element X whose atomic number is 9 (CBSE 2011)
10. On the basis of electronic configuration, how will you identify the first and the last element of a period? (CBSE 2011)