What element is the most chemically reactive?

Mongolia

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Clarification of Question by mongolia-ga on 08 Jul 2006 15:02 PDT

Many thanks for all the useful comments and apologies to Pinkfreud for
giving her such a hard time with this question.

I now realise my question is really meaningless as of course it
depends with WHAT it is reacting.

It would appear though that for any two elements Francium and Fluorine
would be an explosive choice.

Mongolia

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Request for Question Clarification by pinkfreud-ga on 08 Jul 2006 15:14 PDT

Mongolia,

No apology is necessary. I didn't feel that you were giving me a hard
time; you just needed a more detailed answer than I was able to give.
You're one of my favorite customers. In order to give me a hard time,
you'd need to set out with the intent of being unpleasant, and somehow
I don't think that is ever going to happen.

I briefly described this question to my husband, who has two degrees
in chemistry. His top-of-the-head response: "How are you defining
'chemically reactive'?"

~Pink

Wasn't it fluorine that killed a lot of scientists who were converting
it into its element form. The lab exploded and it wasn't til after
about a number of labs had exploded that they realised they had to do
this without oxygen? I forget the whole story as you can probably
tell! Oh well

Here is another website that says Fluorine is the most reactive element:
http://www.webelements.com/webelements/elements/text/F/key.html

And here from the same site Caesium and Francium:
http://www.webelements.com/webelements/elements/text/Cs/key.html
http://www.webelements.com/webelements/elements/text/Fr/key.html

Wikipedia agrees:
http://en.wikipedia.org/wiki/Fluorine
http://en.wikipedia.org/wiki/Francium
http://en.wikipedia.org/wiki/Caesium

There doesn't seem to be enough Francium in the world to worry about it.

I'm on Pink's side.

Edejl:

I recall reading Isaac Asimov's "The Search for the Elements" as a
child. In the late 19th century, as I recall, many scientists were
vying to be the first to isolate flourine in elemental form. This was
a tough one. Many died, though my recollection was not because they
made so much to create an explosion, but rather that they made enough
to be poisoned by it, but not enough to demonstrate their success with
the analytical techniques at their disposal. In later years, I learned
to take the prolific Asimov with a grain of salt (NaF?). Since he was
a chemist, this account may have been more accurate than some of his
other popular science and history books.

In what way do you mean by reactive? Flourine is the strongest
oxidising agent, meaning it oxidises (strips electrons off) all other
elements (not necessarily all compounds - although it does react with
glass). Francium is one of the strongest reducing agents, meaning that
it loses an outer eletron very easily to other elements. One way to
look at this is that to get the most 'explosive' reaction, one should
mix Francium with Flourine. Both become much more stable when the
respectively lose and gain an electron.

flourine is more rective than oxygen (due to the pauling scale)
flourin is rated as the most rective element as it has the greatest
attraction for electrons.
eg.
rocket engines wor by oxidising hydrogen (regular combustion)
producing H2O BUT!.....if a rocket used Hydrogen and flourine it would
gain a much better power/weight raito! (producing HF instead of
water!)

NB. due to all the PC people NASA and others use what they do beacause
HF is poisonous! (however it would have no real health effect on the
population of any country!)