What is the name of the hybrid orbitals used by chlorine in clf3?

Sp^3d

Explanation:

Sp^3d hybridization invovles ther combination of 1s, 3p and 1d orbital  to result in the production of sp3d orbital in which three lobes are oriented towards the corners of a triangle and the other lie perpendicular to them to minimize the repulsions. An important and relatively common type of this hybridization is found in Clf3.

In ClF3  (Chlorine Trifluoride), The central atom Cl needs three unpaired electrons to bond with three F-atoms. ClF3 consist of 3 bond-pairs and 2 lone-pairs. Here, one of the paired electrons of Cl in the 3p subshell remains as a lone pair or unpaired. During hybridisation, one 3s, three 3p and one of the 3d orbitals participate in the process which leads to the formation of five sp3d hybrid orbitals. Here two hybrid orbitals will contain a pair of electrons and three hybrids will contain unpaired electrons which will again overlap with the 2p orbital of F to form single bonds.