- It determines the composition of a molecule of the Compound, with the symbols of the elements present in it.
- When a metal and a non metal combine it result in the formation of Ionic Compound. The compounds that are formed by Ions.
- The ions present in KNO3 (Potassium nitrate) are K⁺ & NO3ˉ
- Rules for writing chemical formula of Ionic Compound:
- Metal element is followed by non metal element.
- Metal element is named as such as it is, but the non-metal is modified. Like- chloride, oxide, nitrite etc.
- NaCl is written and named as Sodium chloride.
- To write the formula of a compound we should know the valency of an atom.
- Metals have the tendency to lose electrons whereas non metals have the tendency to gain electrons.
- A COMPOUND WHICH IS MADE UP OF TWO ELEMENTS IS CALLED BINARY COMPOUNDS.
- When an element contains more than one atom, prefixes are added to them after the 1st element i.e. a word is used before the naming of the compound.
H2S is written as Hydrogen sulphide and not as hydrogen disulphide, it shows that if hydrogen being the 1st element no prefix is added.