Select the best answer for the question.

The valence of aluminum is +3, and the valence of chlorine is -1. The formula for aluminum chloride is correctly written as:

A. [tex]$AlCl_3$[/tex]
B. [tex]$Cl_3Al$[/tex]
C. [tex][tex]$ClAl_3$[/tex][/tex]
D. [tex]$Al_3Cl$[/tex]



Answer :

To determine the correct formula for aluminum chloride, it's important to understand the concept of valence, which indicates the combining capacity of an element to form compounds. Here, we’ll go through the step-by-step process:

1. Identify the valence electrons:
- Aluminum (Al) has a valence of +3. This means that an aluminum atom tends to lose three electrons to obtain a stable electron configuration.
- Chlorine (Cl) has a valence of -1. This means that a chlorine atom tends to gain one electron to obtain a stable electron configuration.

2. Determine the ratio of atoms needed to balance the charges:
- To balance the +3 charge of one aluminum ion, you need three chlorine ions because each chlorine ion has a -1 charge.

3. Form the compound by balancing the charges:
- One aluminum ion (Al^3+) binds with three chloride ions (3 Cl^-). This creates a neutral compound where the total positive charge from aluminum (+3) is perfectly balanced by the total negative charge from the three chloride ions (3 x -1 = -3).

4. Write the chemical formula:
- The correct chemical formula for aluminum chloride that combines these ions in the correct proportion is [tex]\( AlCl_3 \)[/tex].

Given the options provided:
- A. [tex]\( AlCl_3 \)[/tex]
- B. [tex]\( Cl_3AI \)[/tex]
- C. [tex]\( ClAl_3 \)[/tex]
- D. [tex]\( Al_3Cl \)[/tex]

The correct answer is:
A. [tex]\( AlCl_3 \)[/tex]