An element ‘M’ with electronic configuration (2, 8, 2) combines separately with (NO 3 ) – , (SO 4 ) 2– and (PO 4 ) 3– radicals. Write the formula of the three compounds so formed. To which group and period of the Modern Periodic Table does the elements ‘M’ belong? Will ‘M’ form covalent or ionic compounds? Give reason to justify your answer.
Answer
The electronic configuration of M is 2, 8, 2 .
Valency of M = 2
Reaction of M with (NO 3 ) -
The valency of (NO 3 ) - is 1.
So,the compound formed will be M(NO 3 ) 2
Reaction of M with (SO 4 ) 2-
The valency of (SO 4 ) 2- is 2.
So, the compound formed will be MSO 4
Reaction of M with (PO 4 ) 3-
The valency of (PO 4 ) 3- is 3.
So, the compound formed will be M 3 (PO 4 ) 2
Group and Period
Since M has a valency of 2, it belongs to Group 2.
As the number of shells is 3, M belongs to Period 3.
Covalent or Ionic compounds?
M has a tendency to donate electrons to become stable and so it forms ionic bonds .