Which of the following best describes the Lewis structure of ${\mathrm{AlCl}}_3$?

• A. $\mathrm{Al}$ is surrounded by three $\mathrm{Cl}$ atoms, each bonded by a single bond, and $\mathrm{Al}$ has one lone pair.
• B. $\mathrm{Al}$ is surrounded by four $\mathrm{Cl}$ atoms, each bonded by a single bond.
• C. $\mathrm{Al}$ is surrounded by three $\mathrm{Cl}$ atoms, each bonded by a double bond, and $\mathrm{Al}$ has one lone pair.
• D. $\mathrm{Al}$ is surrounded by three $\mathrm{Cl}$ atoms, each bonded by a single pair of electrons, and $\mathrm{Al}$ has no lone pairs.

Answer: (D)

Verified step by step guidance

1. Step 1: Identify the central atom and its valence electrons. Aluminum (Al) is the central atom with 3 valence electrons because it is in group 13 of the periodic table.
2. Step 2: Determine the number of valence electrons for each chlorine (Cl) atom. Each Cl atom has 7 valence electrons since it is in group 17.
3. Step 3: Draw single bonds between the Al atom and each of the three Cl atoms. Each single bond represents a pair of shared electrons (2 electrons). This accounts for 6 electrons shared between Al and Cl atoms.
4. Step 4: Complete the octet for each Cl atom by adding lone pairs around them. Each Cl needs 3 lone pairs (6 electrons) to complete its octet, since each already shares one pair with Al.
5. Step 5: Check the total electrons around Al. Aluminum has 3 single bonds (6 electrons) but no lone pairs, resulting in an incomplete octet (6 electrons instead of 8), which is common for Al in AlCl3.