What element forms an ion with an electronic configuration of 1s22s22p63s23p6 (or [Ar]) and a –2 charge? Give the symbol for the element
element symbol

Sulfur (S)

Explanation: An ion with the same electron configuration as Ar has the same number of electrons as Ar. Because the ion has a −2 charge, a neutral atom of the element has 2 fewer electrons than Ar. The number of electrons in a neutral atom is equal to the atomic number. When sulfur, S, gains two electrons, it has the same configuration as Ar. Sulfur has an electron configuration of 1s²2s²2p⁶3s²3p⁴   (1s2 2s2 2p6 3s2 3p4) meaning it is 2 away from having a noble gas configuration (its charge is −2). So the ion's configuration is 1s²2s²2p⁶3s²3p⁶     (1s2 2s2 2p6 3s2 3p6).  Alternately, this can be written as [Ne]3s²3p⁶ or [Ar].