|Class 9 Chemistry Atoms and Molecules||Writing chemical formula|
Writing chemical formula
In the above formulas Rule I is followed i.e. cross multiply the valencies of the elements to form the formula of the respective compound.
Where Mg (magnesium) is a metal and Cl (chlorine) is a non-metal.
Since the number of polyatomic ion is one therefore no brackets are required.
The formula for calcium hydroxide is Ca(OH)2. The brackets around oh with subscript 2 implies the presence of two hydroxyl group joined to one calcium atom.