Question

Based on the group valency of elements state the formula for the following giving justification for each:
(i) Oxides of $1^{st}$ group elements.
(ii) Halides of the elements of group 13, and
(iii) Compounds formed when an element of group 2 combines with, an element of group 16

Answer 1

(i) Valency of group 1 elements: 1
Valency of oxygen: 2
Oxides of group 1 elements:

Formula of the oxides of group 1 is $M_{2}O$, where M is the group 1 element and O is oxygen.
(ii) Valency of group 13 elements: 3
Valency of halogens: 1
Halides of group 13 elements:

Formula of the halides of group 13 is $M{X}_3$, where M is the group 13 element and X is halogen
(iii) Valency of group 2 elements: 2
Valency of group 16 elements: 2
Compounds of group 2 and group 16 elements:

Formula of the compounds of group 2 and 16 is MN, where M is the group 2 element and N is the group 16 element