How do molecules form?

How do you know how reactive molecules can be when in free radical form?

• Some radicals aren't that "bad" supposedly, like antioxidants which become radicals after stabilizing other radicals but don't do subsequent damage like other radicals can. How to know how "bad" or reactive a particular molecule would be if it were to become a radical?

• Answer:

  It depends on the environment. Free radicals are categorically very reactive. Looking at the periodic table, elements on the far right are unreactive, and elements not in group 18 increase their electronegativity as you go from left to right, and from bottom to top. The higher the electronegativity, the stronger the element will be attracted to electrons. Elements with high electronegativity react most violently with those that have a very low electronegativity.