Question

a student is modeling the units in the formula for aluminum sulfide using the spheres shown below to represent aluminum (al) and sulfur (s) atoms. which model correctly shows a stable ionic compound for aluminum sulfide?

Explanation:

Step1: Determine ion - charges

Aluminum (Al) is in Group 13 and forms a $Al^{3 + }$ ion. Sulfur (S) is in Group 16 and forms a $S^{2 - }$ ion.

Step2: Balance charges

To form a neutral ionic compound, the total positive charge must equal the total negative charge. The least - common multiple of 3 and 2 is 6. So, we need 2 $Al^{3+}$ ions (total charge = $2\times( + 3)=+6$) and 3 $S^{2 - }$ ions (total charge = $3\times(-2)= - 6$). The formula for aluminum sulfide is $Al_2S_3$.

Answer:

The model that shows 2 aluminum ions ($Al^{3 + }$) and 3 sulfur ions ($S^{2 - }$) correctly represents the stable ionic compound for aluminum sulfide. Since no other models are shown in the question - prompt, if the model in option A shows 2 $Al^{3+}$ and 3 $S^{2 - }$ it is the correct one. Without seeing all options, we can't fully determine the correct choice from the given information, but the correct ratio of ions is 2 $Al^{3+}$ to 3 $S^{2 - }$.