Answer:
Argon
Explanation:
The atomic number of sulfur is 16. A neutral S atom has 16 protons and 16 electrons. The formula for the sulfide ion is S2−, so it has gained to electrons for a total of 18. Its electron configuration is 1s22s22p63s23p6.
This is the same electron configuration for a neutral Argon atom, which has atomic number 18; 1s22s22p63s23p6. Argon is a noble gas, and the representative elements (groups 1,2,13-18, or the A groups) form ions that are isoelectronic with their closest noble gas.
