Consider the following elements of third period of modern periodic table :
`{:("Period III elements ",Na,Mg,Al,Si,P,S,Cl,Ne),("Atomic number ",11,12,13,14,15,16,17,18):}`
How does valency very in a period on going from left to right ?

Find out the valencies of first 20 elements : How does the valency vary in a period on going from left to right ?

How does atomic radius of an element vary across a period from left to right ?

How are the elements divided into s, p, d and f – blocks in the Modern periodic table ?

How does the position of element in the periodic table useful in finding valency and oxidation number?

In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these have physical and chemi al properties resembling calcium ?

Elements of one short period of the periodic Table are given below in the order from left to right . Li , Be,B,C,n,F,Ne Answer the following : To which period , do these elements belong ?

Which of the following statements about the modern periodic table are incorrect ? (a) The elements in Modern periodic table are arranged on the basis of their decreasing atomic number. (b) The elements in Modern periodic table are arranged on the basis of their increasing atomic masses. (c) Isotopes are placed in adjoining groups in the periodic table. (d) The elements in the modern periodic table are arranged on the basis of their increasing atomic number.

Answer the following question based on the values of the atomic radii of the elements of one of the periods in modern periodic table Li ( 152 ) , Be (111) B, (88) , C (77) ,N (74) ,o (66 ) and F (64) In the numerical listing of periods in the modern periodic table , what number was given to above elements ?

Elements of one short period of the periodic Table are given below in the order from left to right . Li , Be,B,C,n,F,Ne Answer the following : one element of this period is missing . Which is the missing element and where it should be placed ?

Identify the correct statements from the following. (i) In the periodic table, about 78% of elements are metals. (ii) In a group, the metallic character decreases from top to battom and in a period the non-metallic character decreases from left to right. (iii) The element Ho belongs to f-block.