‘Valency is also the number of electrons – donated or accepted by an atom so as to achieve the stable electronic configuration of the nearest noble gas’. With reference to this definition –
State why the valency of chlorine, oxygen and nitrogen is: −1, −2 and −3 respectively.
Valency of an element is the number of electrons accepted to achieve stable configuration of nearest noble gas.
Chlorine accepts 1 electron and has valency −1 where as oxygen accepts 2 electrons the valency of oxygen is −2 and nitrogen accepts 3 electrons, valency of nitrogen is −3.