Question

The following diagram shows a part of the periodic table in which the elements are arranged according to their atomic numbers. (The letters given here not the chemical symbols of the elements):

a 3	b 4		c 5	d 6	e 7	f 8	g 9	h 10
i 11	j 12		k 13	l 14	m 15	n 16	o 17	p 18

(i) Which element has a bigger atom, a or f?
(ii) Which element has a higher valency, k or o?
(iii) Which element is more metallic i or k?
(iv) Which element is more non-metallic, d or g?
(v) Select a latter which represents a metal of valency 2.
(vi) Select a letter which represents a non-metal of valency 2.

Answer 1

(i) Element a has a bigger atom. In the periodic table, the atomic radius of the element decreases on moving from left to right in a period.

(ii) k has a higher valency.
    
     Electronic configuration of k : K L M
                                                   2 8 3
     Therefore, valency for k = valence electron of K = 3
   
     Electronic configuration of o: K L M
                                                  2 8 7
     Therefore, valency for o = 8 - valence electron of o
                                          = 8 - 7 = 1
   

(iii) The element i is more metallic because i belongs to the left side and group 1 of the periodic table. On moving from left to right in a period, the metallic character decreases.

(iv) The element g is more non-metallic, because the non-metallic character increases on moving from left to right in a period.

(v) The elements b or j are metals with a valency of 2 as they have 2 valence electrons and are placed on the left side of periodic table.

(vi) The elements f or n are metals with a valency of 2 .

 Electronic configuration of f : K L
                                              2 6   
 Valency of f = 8 - valence electron
                   = 8 - 6 = 2
 
Electronic configuration of n : K L M
                                              2 8 6
Valency of n = 8 - valence electron
                   = 8 - 6 = 2