(i) Select the letter which represents a halogen. (ii) Select the letter which represents a noble gas. (iii) What type of bond is formed between a and b? (iv) What type of bond is formed between c and b? (v) Which element will form a divalent anion?
In the following diagram for the first three periods of the periodic table, five elements have been represented by the letters a, b, c, d and e (which are not their chemical symbols):
1
18
2
13
14
15
16
17
a
b
c
d
e
(i) Select the letter which represents a halogen. (ii) Select the letter which represents a noble gas. (iii) What type of bond is formed between a and b? (iv) What type of bond is formed between c and b? (v) Which element will form a divalent anion?
(i). The letter that represents halogen is "b" as it lies in group 17 with 7 valence electrons.
(ii).The element that is noble gas is "e" as it lies in group 18 with 8 valence electrons.
(iii) The bond formed between a and b is covalent as a belongs to group 14 with 4 valence electrons and b belongs to group 17 with valency -1. As both are nonmetals, they will form a covalent bond by sharing electrons.
(iv) The bond formed between c and b is ionic as c belongs to group 2 with valency +2 and b belongs to group 17 with valency -1. As c is a metal and b a nonmetal, so electron transfer will occur from metal to nonmetal and an ionic bond is formed.
(v) "d" will form a divalent anion as it belongs to group 16 with 6 valence electrons, therefore its valency is -2.