Question

what is the chemical formula for aluminum fluoride? a $\ce{al_{3}f}$ b $\ce{alf_{3}}$ c $\ce{al_{2}f_{3}}$ d $\ce{alf}$

Explanation:

Step1: Identify ion charges

Aluminum forms $\text{Al}^{3+}$; fluorine forms $\text{F}^-$

Step2: Balance charge neutrality

3 $\text{F}^-$ ions balance 1 $\text{Al}^{3+}$ ion

Step3: Write the formula

Combine symbols with subscripts for charge balance

Answer:

B. $\text{AlF}_3$