question_answer

 (i) State the method of determining the valency of an element if its atomic number is given. (ii) Determine the valency of the following elements, the atomic numbers of which are given in parenthesis: Chlorine (17), Sulphur (16), Aluminium(13)

Answer:

                (i) The number of electrons gained, lost or shared to make the octet of electrons (in the outermost shell), gives us directly the combining capacity of the element, that is, the valency.                 (ii)                                          

Elements	Atomic no.	Electronic configuration	Valency
Chlorine	17	2,8,7	-1
Sulphur	16	2,8,6	-2
Aluminium	13	2,8,3	+3