CHEMISTRY COMMUNITY

When I am predicting the type of hybrid orbital for lets say H3O+, can I just say sp^3? Or do I have to say 2sp^3 because O is in the second period of the period table?

it would just be sp^3. You only want to look at how many regions of electron density there are with hybridization, not at where the elements are in the periodic table. Since there are 4 regions of electron density, the hybridization is sp^3