Charged and uncharged molecules?

[ajw614]

Hi everyone. I am more of a biologist. Any help would be very appreciated on the below questions.

I am trying to understand the chemistry behind certain reactive oxygen and nitrogen species in the body. I have questions regarding nitric oxide, hydrogen peroxide and superoxide.

1. Nitric oxide is a free radical, but it is uncharged. I don't understand this from looking at the lewis structure. Can soemone explain this to me. Im assuming I don't fundamentally understand what makes a molecule charged and uncharged. Superoxide is a radical and charged - how is this so?

2. H₂O₂ is a reactive oxygen species, but not a radical. In fact, on looking at the molecule; it looks stable and symetrical. I've read that its polarity can be attributed to bond angles and that the lewis structure doesn't explain the polarity of H₂O₂; can someone explain this to me please?

3. Oxygen is obviously very electronegative and reactive. Why can molecular oxygen be reduced to superoxide - i.e one of the oxygens would have 9 outer shell electrons and therefore not follow the octet rule. Does the electronegativity of the two oxygens not just cancel each other out, making it stable. Essentially my question is why is molecular oxygen so reactive from a chemistry perspective.

Any help on these questions would be very much appreciated.

Thanks.

Cell Signal 74