Question

The electronic configurations of three elements A, B and C are as follows:

A	2, 8, 1
B	2, 8, 7
C	2, 4

(a) Which of these element is a metal?
(b) Which of these elements are non-metals?
(c) Which two elements will combine to form an ionic bond?
(d) Which two elements will combine to form a covalent bond?
(e) Which element will form an anion of valency 1?

Answer 1

(a) Element A is a metal because it can donate its one electron to attain noble gas configuration.

(b) Elements B and C are non-metals because B and C can complete their octets either by accepting or sharing the electrons.

(c) Elements A and B will combine to form an ionic bond because element A will transfer its electron to element B to attain noble gas configuration.

(d) Elements B and C will combine to form a covalent bond by sharing four electrons of one atom of element C with four atoms of element B.

(e) Element B will form an anion of valency one because element B contains one less electron to complete its octet. After gaining one electron, it becomes stabilised and forms an anion B^$-$.