What would be the atomic number of the next halogen if discovered in future?

The next halogen will have$7s^{2}7p^5$ outer configuration. Once the 5f and $6\mathrm{d}$-orbitals are completely filled then only the fillings of 7p-orbitals will begin. So, the atomic number of the new halogen will be 112 for the fillings of $6\mathrm{d}$-orbitals and then plus 5 to get the required atomic number i.e. 117.