Question

The electronic configurations of three elements A, B and C are as follows:
$$\begin{array}{cc}A& 2,8,1\\ B& 2,8,7\\ C& 2,4\end{array}$$

(a) Which of these elements is a metal?
(b) which of these elements are non-metals?
(c) Which two elements will combine to form an ionic bond?
(d) Which tow 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 a 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 $B^{-}$