Question

which is the correct lewis structure for phosphorus trichloride (pcl₃)? 10 choose the best answer. which of these represents the three - dimensional shape of atoms in a molecule? lewis structure molecular geometry vsepr theory resonance and formalion

Explanation:

Step1: Calculate total valence electrons

Phosphorus (Group 15) has 5 valence electrons; each Chlorine (Group 17) has 7 valence electrons. For $\text{PCl}_3$:
$5 + (3 \times 7) = 5 + 21 = 26$ total valence electrons.

Step2: Assign bonds and lone pairs

Form 3 single P-Cl bonds (uses $3 \times 2 = 6$ electrons). Remaining electrons: $26 - 6 = 20$ electrons. Each Cl gets 3 lone pairs ($3 \times 6 = 18$ electrons), leaving 2 electrons as 1 lone pair on P. No double bonds are needed, as P can accommodate an expanded octet with its lone pair and 3 single bonds, satisfying all atoms' octets (or duet for H, not applicable here).

Step3: Match to correct structure

The structure with 3 single P-Cl bonds, 3 lone pairs on each Cl, and 1 lone pair on P matches the first option.

The three-dimensional shape of atoms in a molecule is defined by the spatial arrangement of its bonded atoms, which is described by molecular geometry. Lewis structure only shows 2D bonding, VSEPR theory is the method to predict shape, and electron dot notation is a simplified bonding representation.

Answer:

The first option: $\underset{\cdot \cdot}{\overset{\cdot \cdot}{\text{Cl}}}-\underset{\cdot \cdot}{\text{P}}-\underset{\cdot \cdot}{\overset{\cdot \cdot}{\text{Cl}}}$ (with 3 lone pairs on each outer Cl, 1 lone pair on P, and the third Cl attached to P with 3 lone pairs)

---

For the second question: