Determine the chemical formula of aluminium chloride.

Sure, let's determine the chemical formula of aluminum chloride step by step:

1. Identify the elements involved:

   • Aluminum (Al)
   • Chlorine (Cl)

2. Determine the valency of each element:

   • Aluminum is in Group 13 of the periodic table and has a valency of +3.
   • Chlorine is in Group 17 of the periodic table and has a valency of -1.

3. Balance the charges to form a neutral compound:

   • Aluminum has a charge of +3.
   • Chlorine has a charge of -1.
   • To balance the charges, we need three chlorine atoms to balance the +3 charge of one aluminum atom.

4. Write the chemical formula:

   • One aluminum atom (Al) will combine with three chlorine atoms (Cl) to form aluminum chloride.
   • Therefore, the chemical formula is AlCl₃.

So, the chemical formula of aluminum chloride is AlCl₃.