This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
There are 7 electrons in the highest occupied energy level of a neutral chlorine atom. 

1st energy level takes two electrons
2nd energy level takes eight electrons
3rd energy level takes eighteen electrons
Take note: The atomic number of an element is equal to its electrons. Since chlorine has an atomic number of 17 so it has also 17 electrons..