What is the Lewis Structure for PCl5?

The Lewis structure for PCl₅ (phosphorus pentachloride) can be drawn by following these steps:

1. Determine the total number of valence electrons: Phosphorus (P) has 5 valence electrons, and each chlorine (Cl) atom has 7 valence electrons. Since there are 5 chlorine atoms, the total number of valence electrons is 5 (from P) + 5 × 7 (from Cl) = 40 electrons.
2. Place the least electronegative atom in the center: Phosphorus is less electronegative than chlorine, so it will be the central atom.
3. Connect the outer atoms to the central atom with single bonds: Draw single bonds between phosphorus and each of the five chlorine atoms. This uses up 5 × 2 = 10 electrons, leaving 30 electrons.
4. Distribute the remaining electrons: Place the remaining 30 electrons around the chlorine atoms to complete their octets. Each chlorine atom will have 3 lone pairs of electrons.
5. Check the octet rule: Phosphorus has 10 electrons around it (5 bonds), which is acceptable because it can have an expanded octet due to its ability to use d-orbitals.

Here is the Lewis structure for PCl₅:

    Cl
    |
Cl—P—Cl
    |
    Cl

In this structure, phosphorus is surrounded by five chlorine atoms, each with three lone pairs of electrons.