 Astatine's 6p subshell split is only 3.8 eV, and its 6p1/2 chemistry has already been called "limited".These effects cause tennessine's chemistry to differ from those of its upper neighbors (see below).Tennessine's first ionization energy—the energy required to remove an electron from a neutral atom—is predicted to be 7.7 eV, lower than those of the halogens, again following the trend.