Question

Electronic configurations of four elements A, B, C and D are given below:

(1) $1s^{2}2s^{2}2p^{6}$
(2) $1s^{2}2s^{2}2p^{4}$

(3) $1s^{2}2s^{2}2p^{6}3s^{1}$
(4) $1s^{2}2s^{2}2p^{5}$

Which of the following is the correct order of increasing tendency to gain electron?

• A. A < C < B < D
• B. A < B < C < D
• C. D < B < C < A
• D. D < A < B < C

Answer 1

Answer: (A)

A < C < B < D

Answer 2

: $AisNe(10):1s^{2}2s^{2}2p^{6}$

$BisO(8):1s^{2}2s^{2}2p^{4}$

$CisNa(11):1s^{2}2s^{2}2p^{6}3s^{1}$

$DisF(9):1s^{2}2s^{2}2p^{5}$

Noble gases (1) have completely filled orbitals hence, they have no tendency to gain electrons. Element C prefers to lose electron $(3s^{1})$ to attain stable noble gas configuration.

Element D has only 1 electron less than stable noble gas configuration. Thus, it has greater tendency to gain electron than element B which has 2 electrons less than noble gas configuration. Thus, the correct order of increasing tendency to gain electron is: A < C < B < D.