The Chlorine trifluoride should consist of 2 lone-pairs and 3 bond-pairs. The central atom, Cl, requires three unpaired electrons to bond with three F-atoms. One 3s, three 3p, and one of the 3d orbitals of Cl participate in the hybridization, and thereby, five sp3d hybrid orbitals are formed.
The structure of ClF3 is as follows:
