Question

Elements X, Y and Z have atomic numbers 6, 9 and 12 respectively. Which one :

(a) forms an anion (b) forms a cation

(c) has four electrons in its valence shell ?

Answer 1

A. The element Z has an electron configuration, $1s^{2}2s^{2}2p^{6}3s^2$ , so it will form a cation by losing 2 electrons, to form a +2 charge.

B. The element Y has an electron configuration, $1s^{2}2s^{2}2p^5$ , so it will form an anion by gaining 1 electron to complete its octet and form a -1 charge.

C. The element X has an electron configuration $1s^{2}2s^{2}2p^2$ . So X has 4 electrons in its valence shell.