# What is the Lewis Dot Structure for Phosphorus trichloride?

There are $3 \times 7 + 5 = 26$ valence electrons to distribute, i.e. $13 \text{ electron pairs}$.
Around EACH bound $C l$ atom there are 3 lone pairs; there are $3 \times P - C l$ bonds; the thirteenth lone pair resides on phosphorus: $: P {\left(- C l\right)}_{3}$. Since there are 4 electron pairs around phosphorus, the geometry is based upon a tetrahedron, but since one of these electron pairs is a stereochemically active non-bonding pair, the geometry around phosphorus is described as trigonal pyramidal.