Chlorine has a smaller atomic size.
Explanation: As you move towards right of the periodic table, the atomic size decreases. This is because the number of protons is increasing towards the right of the periodic table, which applies a greater inward force on the electrons. that is why the elements on the right of the periodic table have a smaller atomic size when compared to the elements on the left. Since chlorine is on the right side of aluminium, it has a smaller atomic size.
Because you need to know what you are looking for before actually trying something so you can prevent any accidents by doing stuff at random
