Question

try it: valence electrons
halogens are very reactive. these elements all have electrons in their energy level. they are very reactive because
they only need more electrons to have a perfect outer shell.
possible points: 2

Explanation:

Step1: Recall halogen valence electrons

Halogens are in group 17 of the periodic table.

Step2: Determine valence - electron number

Elements in group 17 have 7 electrons in their outer (valence) energy level.

Answer:

7