What happens when a chlorine atom gains an electron in its outer energy shell? A. It becomes a negative ion.

B. It has a decrease in the number of neutrons.

C. It becomes a positive ion.

D. It has an increase in the number of protons.

A.

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.

A

Explanation:

When a element gain a electron it is nation as it is now negatively charged

a bird that nests only in a particular tree species.