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Carl Heinzl <heinzl@sw*.st*.co*> wrote (Subject: Re: O2 Toxicity/free
radicals):-

> ... A free radical is ... an atom or molecule that has a valence shell with
> one unpaired binding electon. ... A simple example of a free radical occurs
> when we had light to chemicals such as Boron (Br2). When Br2 splits, it does
> so via a heterolytic cleavage and leaves each Boron atom with 7 electrons in
> its valence shell.

`Br' is BROMINE!!!, a liquid halogen. It behaves as you say. Boron is `B', a
solid, and its chemistry is different. It has a very odd habit of sharing
electrons between THREE atoms in stable compounds, so that, with 3 valency
electrons each, each atom ends up with a share in 8 electrons; it refuses to
go metallic. It likes arranging 12 boron atoms in a hollow sphere. It absorbs
neutrons at a great rate, and thus metal borides are used to make control
rods for nuclear reactors.

`heterolytic': `hetero-' = "the other" in Greek: surely this means cleavage to
a Br+ and a Br- to keep the electrons paired, rather than to two neutral Br?

> ... the chemical makeup of a "superoxide anion" so I cannot determine if it
> is a free radical ...

The superoxide ion is O2-, an oxygen molecule with one more electron, i.e. it
is a free radical. Potassium will form a superoxide if burnt, sometimes. I
read that if potassium superoxide is used as rebreather absorbent, as it
absorbs CO2 and water vapour it gives off more than the oxygen that the diver
used up in making that CO2 and water vapour. There once was a make of oxygen
rebreather called `Oxylite' that worked that way instead of having an oxygen
cylinder, I read once; probably intended as an industrial or coalmine rescue
set, but it was used for diving early this century when the first time a film
of `20000 Leagues under the Sea' was made.

The ordinary oxygen molecule is a bit like a divalent free radical; but as
this is techdiver and not tech_quantum_mechanics, I will leave it there.

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