Question

Derive the molecular formulae of the following compounds stepwise and give their atomicity.

Iron(II) carbonate

Answer 1

Derive the molecular formulae of Iron(II) carbonate stepwise and give their atomicity:

1. Write the symbols of the elements or the ions forming the compound.
$\mathrm{Fe}$ ${\mathrm{CO}}_3$
2. Write the valency of each as a superscript to the top right. Ignore the + and - signs of ions.
${\mathrm{Fe}}^2$ ${{\mathrm{CO}}_3}^2$
3. Interchange the valencies and bring them down diagonally.

4. Write the interchanged valencies as subscripts. Place polyatomic ions in parentheses if the subscript is greater than 1.

${\left(\mathrm{Fe}\right)}^2{\left({\mathrm{CO}}_3\right)}^2$

5. Ignore the number 2, subscript. Reduce the numbers to the lowest ratio. Write the chemical formula.
${\mathrm{FeCO}}_3$

Atomicity: Atomicity is the total number of atoms in a molecule. Molecules may be monoatomic, diatomic, triatomic, or polyatomic depending on the number of atoms.