List the first 4 halogens as they appear in the periodic table as they appear. What does your answer suggest about their relative reactivity?

Fluorine, Chlorine, Bromine, IodineIf you write the electronic structure to start, F = 2,7, Cl = 2, 8, 7, Br = 2, 8, 8, 7, I = 2, 8, 8, 8, 7. This shows that they all have 7 outer electrons so we can tell they all want to gain an extra electron to achieve the magic full set of electrons. As Fluorine has the least amount of electrons this means the outer electrons are closest to the nucleus. Remember opposites attract, so the positive protons in the nucleus are going to pull electrons towards them. As they will be closer to other electrons (on other atoms) they will be better at pulling them off and therefore more reactive. If we follow this rule the reactivity will DECREASE as you move downwards in the periodic table as the nucleus gets further away from where it needs to pull.