Chapter 4 Question 35

[Lexy Swenson 1F]

For part D of this question it asks to identify the hybrid orbitals used by the atom Se in SeF3+. The answer solution says it is sp3, but sp3 is for tetrahedral and wouldn't this species not be a tetrahedral because there are only three regions of electron density?
Not sure if I am misunderstanding the shape of this molecule, can someone help?
Thanks!

[Lauren Trent 2A]

sp3 is not necessarily for a tetrahedral shape, it is for any molecule with 4 regions of electron density. In this case, Se has 3 bonds, a single bond with each of the three F atoms, and a lone pair in order to satisfy the octet rule and the 26 electrons for the molecule. The 3 single bonds plus the lone pair make 4 regions of electron density, therefore it is sp3 hybridized. Hope this helps!