Group 7. Your world, with a twist. The group of oddities.
Group 7 elements are not one bit alike one another. Technetium and Bohrium are the synthesized elements in this group. Both are extremely rare (bohrium is impossible to find) and highly radioactive, while manganese and rhenium are not as rare nor radioactive. Manganese is the most common element in this group, and is a mineral that can be found as a trace element in human bodies. Rhenium has the highest melting point out of all of the others. Manganese is used in ferromagnetic alloys, while rhenium is used in wires for flash photography. Technetium can be found on red giant stars while rhenium and manganese can be found on the Earth. Manganese is found on meteorites as well.