Due to the spin-orbit splitting of the 7p subshell being very large in flerovium, and the fact that both flerovium's filled orbitals in the seventh shell are stabilized relativistically, the valence electron configuration of flerovium may be considered to have a completely filled shell. Its first ionization energy of should be the second-highest in group 14. The 6d electron levels are also destabilized, leading to some early speculations that they may be chemically active, although newer work suggests that this is unlikely. Because this first ionisation energy is higher than that of silicon and germanium, though still lower than that for carbon, it has been suggested that flerovium could be classified as a metalloid.