The atomic numbers of five elements A, B, C, D and E are 6 , 8 , 3 , 7 and 9 respectively. (i) Which is the element having the highest electropositivity among these elements? Why? (ii) Which is the element having the least metallic character among these elements? Why? (iii) What is your conclusion about the relationship between metallic character and electropositivity of an element?

(i) The element having the highest electropositivity among the given elements is C. Its atomic number is 3 and this element comes first in the second period. The electropositivity decreases along the period. The electronic configuration of C is 2 , 1 . It has only one electron in the outermost shell & can donate it to form a mono positive ion. (ii) The element having the least metallic character among the given elements is E. Its atomic number is 9 . This element is towards the end of the second period. The metallic character decreases across a period from left to right. The electronic configuration of E is 2 , 7 . It can accept one electron to obtain the octet configuration. (iii) Electropositivity is the tendency of an atom to donate electrons to form positively charged cations. Electropositivity is directly proportional to the metallic character. As the electropositivity increases metallic character also increases. Generally, metals are electropositive and non-metals are electronegative.

Observe the given table and answer the following question: Elements A B C D E Atomic number 11 4 2 7 19 Identify the two elements that belong to the same period and the two elements that belong to the same group. Give a reason for your conclusion.

From the given table, elements A and E ate belongs to the same group because in both last shells i.e. outermost shell the valency is one; therefore it belongs to the same group. And elements D and B belong to the same period because both have the same shell and i.e, two.