The atomic numbers of Al and Cl are 13 and 17 respectively

Explanation:

Aluminium(Al) is 2,8,3 while chlorine(Cl) is 2,8,7

When atom loses electrons it gains a positive  charge

When atom gains electrons it gains a negative charge

So, Al³⁺ is 2,8 and total electrons = 2+8 = 10

Cl^- is 2,8,8 and total electrons = 2+8+8 = 18

Final Answer:

Total electrons in Al³⁺ = 10

Total electrons in Cl^- = 18