To determine the correct formula for aluminum chloride, we need to balance the charges of aluminum (Al) and chlorine (Cl). Here is a detailed step-by-step solution:
1. Understand the Valences:
- The valence of aluminum (Al) is +3.
- The valence of chlorine (Cl) is -1.
2. Balancing the Charges:
- To form a neutral compound, the total positive charge must equal the total negative charge.
- Aluminum has a valence of +3, so one aluminum atom contributes +3.
- Each chlorine atom has a valence of -1, so to balance the +3 charge of one aluminum atom, we need three chlorine atoms, each contributing -1 (3 * -1 = -3).
3. Write the Formula:
- Therefore, one aluminum atom combines with three chlorine atoms to balance the overall charge.
- The symbols for aluminum and chlorine are Al and Cl, respectively.
- When writing the formula, we place the symbols for aluminum and chlorine together with their respective quantities as subscripts.
4. Correct Notation:
- The correct chemical formula for aluminum chloride is [tex]\( \text{AlCl}_3 \)[/tex].
Given the provided options:
A. [tex]\( \text{Al}_3 \text{Cl} \)[/tex] -- This implies three aluminum atoms and one chlorine atom, which does not correctly balance the charges.
B. [tex]\( \text{Cl}_3 \text{Al} \)[/tex] -- This suggests three chlorine atoms combining with one aluminum atom but in the wrong order.
C. [tex]\( \text{AlCl}_3 \)[/tex] -- This correctly represents one aluminum atom combining with three chlorine atoms, balancing the charges precisely.
D. [tex]\( \text{ClAl}_3 \)[/tex] -- This suggests one chlorine atom combining with three aluminum atoms, which is incorrect.
Therefore, the correct answer is:
C. [tex]\( \text{AlCl}_3 \)[/tex].
