Answer:
[tex]\rm S^{2-}[/tex].
Explanation:
Based on the electron configuration of this ion, count the number of electrons in this ion in total:
[tex]2 + (2 + 6) + (2 + 6) = 18[/tex].
Each electron has a charge of [tex](-1)[/tex].
Atoms are neutral and have [tex]0[/tex] charge. However, when an atom gains one extra electron, it becomes an ion with a charge of [tex](-1)[/tex]. Likewise, when that ion gains another electron, the charge on this ion would become [tex](-2)[/tex].
The ion in this question has a charge of [tex](-2)[/tex]. In other words, this ion is formed after its corresponding atom gains two extra electrons. This ion has [tex]18[/tex] electrons in total. Therefore, the atom would have initially contained [tex]18 - 2 = 16[/tex] electrons. The atomic number of this atom would be [tex]16[/tex].
Refer to a modern copy of the periodic table. The element with an atomic number of [tex]16[/tex] is sulphur with atomic symbol [tex]\rm S[/tex]. To denote the ion, place the charge written backwards ("[tex]2-[/tex]" for a charge of [tex](-2)[/tex]) as the superscript of the atomic symbol:
[tex]\rm S^{2-}[/tex].
