Using the periodic table, predict the formulas of compounds which might be formed by the following pairs of elements :
(a) Silicon and bromine
(b) Aluminium and sulphur

Explanation

(a) Silicon is an element of the `14^(th)` group with a valence 4 . Bromine belongs to the `17^(th)` group ( halogen family ) with valence 1. Hence the formula of the compound formed would be SiBr .
(b) Alumjnium belongs to the `13^(th)` group with a valence 3. Sulphur belongs to the `16^(th)` group ( chalcogen family ) with valence 2. Hence the formula of the compounds formed would be `AI_(2)S_(3)` .