Lewis diagram for ClF3
The lewis diagram for clf3 places chlorine as the central atom with three fluorine atoms attached by single bonds. The electron count requires two lone pairs on chlorine and three lone pairs on each fluorine, producing an expanded octet on chlorine and formal charges of zero.
Valence-electron accounting
The total number of valence electrons is obtained from periodic-table group counts: \[ 7 \;(\text{Cl}) + 3 \times 7 \;(\text{F}) = 28 \]
Bonding and lone pairs
Three single bonds consume \(3 \times 2 = 6\) electrons. The remaining \(28 - 6 = 22\) electrons are assigned as lone pairs.
Each fluorine completes an octet with three lone pairs, consuming \(3 \times 6 = 18\) electrons across the three fluorine atoms. The remaining \(22 - 18 = 4\) electrons appear as two lone pairs on chlorine.
Formal-charge check
A compact verification uses \( \text{FC} = V - (N + \tfrac{B}{2}) \), where \(V\) is valence electrons for the free atom, \(N\) is nonbonding electrons in the structure, and \(B\) is bonding electrons.
| Atom | \(V\) | \(N\) | \(B\) | Formal charge |
|---|---|---|---|---|
| Cl (central) | 7 | 4 | 6 | \(7 - (4 + \tfrac{6}{2}) = 0\) |
| F (each) | 7 | 6 | 2 | \(7 - (6 + \tfrac{2}{2}) = 0\) |
Electron geometry and molecular geometry
Five electron domains surround chlorine (three bonding domains and two lone-pair domains). The electron geometry is trigonal bipyramidal, while the arrangement of atoms alone is T-shaped (AX3E2). Bond angles are compressed below \(90^\circ\) and below \(180^\circ\) by lone-pair repulsions.
Common pitfalls
An incomplete Lewis diagram often omits one or both lone pairs on chlorine; the missing lone pairs remove the expanded-octet character and contradict the \(28\)-electron count. Double bonds to fluorine are also inconsistent with fluorine’s strong preference for single bonding and unnecessarily introduce nonzero formal charges.