Explanation: When a chlorine atom gains an electron, its outermost principal energy level achieves an octet. In this case, the ion has the same outermost shell as the original atom, but now that shell has eight electrons in it.
I believe the answer is: Different scientists use different data for investigation. I say that because different scientists have different equipment, ideas, and have different methods. I hope I was right and i hope it helped and i wasn't to late to answer this question.
