Question

1. choose the best answer.

which is the correct lewis structure for phosphorus trichloride (pci₃)?

Explanation:

To determine the correct Lewis structure for \( \text{PCl}_3 \), we analyze the valence electrons and octet rule:

1. Valence Electrons: Phosphorus (P) has 5 valence electrons; each Chlorine (Cl) has 7, so \( 5 + 3(7) = 26 \) total valence electrons.
2. Bonding and Lone Pairs: P forms single bonds with 3 Cl atoms (using \( 3 \times 2 = 6 \) electrons), leaving \( 26 - 6 = 20 \) electrons for lone pairs. Each Cl needs 6 lone electrons (to satisfy the octet, as 2 are used in bonding), so \( 3 \times 6 = 18 \) lone electrons on Cl atoms, and P retains 1 lone pair (2 electrons), totaling \( 6 + 18 + 2 = 26 \) electrons.
3. Structure Analysis:

• The first option (top) shows P with 2 lone electrons (correct) and each Cl with 6 lone electrons (correct octet for Cl, 8 total electrons: 2 bonding + 6 lone).
• Other options fail: e.g., second option has Cl atoms with incorrect lone pairs; third has P with too few lone electrons; fourth has double bonds (unnecessary, as P and Cl form single bonds).

Answer:

The first Lewis structure (with P bonded to three Cl atoms, each Cl having 6 lone electrons, and P having 2 lone electrons) is correct. (Assuming the first option is labeled, e.g., A. [the top structure with P and three Cls, each Cl with 6 lone dots, P with 2 lone dots])