Question

Write the formulae for the following.

Aluminium chloride

Answer 1

Step 1- Writing the symbols elements or the ions that form the compound

Aluminium - $\mathrm{Al}$

Chlorine - $\mathrm{Cl}$

Step 2- Writing the valency of each element or the charge of each ion below its symbol.

$$\begin{gathered} \mathrm{Al}\mathrm{Cl} \\ +3-1 \end{gathered}$$

Step 3- Now interchanging the valencies or charges of the combining atoms or ions.

$$\begin{gathered} \mathrm{Al}\mathrm{Cl} \\ \xcancel{} \\ +3-1 \end{gathered}$$

Step 4- Excluding the positive and negative signs, exchange numbers and write them as subscripts.

${\mathrm{AlCl}}_3$