Element 115 - a Metal
Naturally, element 115 ends up in the main group V of the Periodic Table of the Elements, just below bismuth with its 83 protons, This would imply element 115 representing a rather volatile metal. However, such a simple "theory" needs experimental confirmation, and in fact nuclear chemists have developed methods to determine basic chemical properties (e.g. gas or metal?) based on single atoms - and the TASCA separator at GSI was built for that purpose.
Nevertheless, such single-atom style measurements require the element of interest to live sufficiently long, while the known isotopes of element 115 - those with 172-175 neutrons - are too short lived; well below one second. In the future there might be means to produce isotopes with more and more neutrons, for which nuclear structure theory indicates longer and longer lifetimes until a "magic" neutron number 184 is reached. See notes on this "Island of Stablity" at