Which of the following ions has an electron configuration...
Which of the following ions has an electron configuration different from the other?
17CI-
8O2-
12Mg2+
13AI3+
Correct answer is A
17Cl− = 18 electrons = 2, 8, 8
12Mg2+, 8O2− and 13Al3+ all have 10 electrons = 2, 8.