Compounds And Way To Write Formula For Compounds

         All the matter or substance in the world is made extremely tiny particles called ATOMS. Group of Atoms of same substance or different substance are combinedly called as “COMPOUNDS”.

Chemical formula for molecules or compounds is made by using criss-cross method by using its valency.

With example of compound Sodium Carbonate. The following steps are taken while writing the formula for every compound as of Sodium Carbonate.

1. First see the elements and the number of atoms present to that elements in the given compound or molecule.

2. Write the symbol of each atom in the given compound side by side usually cation first followed by anion. Ex- Na CO₃

3. Write the valency of each atom on the top of its element. Ex- Na¹ (CO₃)²

4. Divide the valency numbers with highest common factor to get simple ratios (like in given example among (1,2)- 1 is the highest common factor)Ex- Na¹ (CO₃)²

5. Interchange the valency of two elements and write the numbers to the lower right of the constituents as subscripts. Ex- Na₂(CO₃)₁

6. If the constituents receive number 1 then ignore it while writing the formula of compound.

7. If the constituents receive 2 or more than 2 atoms enclose it with in brackets and write in as subscripts. Ex- Na₂CO₃

Example-

Formula for some common compounds