Which is the most reactive metal: Caesium or Francium?

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Solution 1

The reactivity series consists of elements whose properties are FULLY known and understood. It is on the basis of whether an element can displace another from its salt solution (this is what you've been told at grade 10 Indian schooling level I guess?). Francium, on the other hand is a radioactive element, with a half life of only 22 minutes for its most stable isotope (Francium-223). Therefore, we can only make predictions, and not observations, about the nature of its salts and whether they would displace other elements from their salt solution or not.

Solution 2

We do not really know. Francium is known only as highly radioactive, short-lived isotopes and we have very little experimentally based chemical information about it. Most of its properties are mere predictions.

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Aryan
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Updated on August 01, 2022

Comments

  • Aryan
    Aryan over 1 year

    I searched on Wikipedia for reactivity series but it showed me Caesium as the most reactive metal. I know and have studied that reactivity increases as we go down the first group. Then shouldn’t it be Francium more reactive than Caesium than the other way around.

    PS: I study in class 10 so please explain in that way only.

    • Aryan
      Aryan over 3 years
      Oscar, if they are mere predictions then can’t we predict that it will be more reactive than Caesium. If you want to you can explain in more detail.
    • ron
      ron over 3 years
      Francium is less reactive due to relativistic effects. This earlier Q&A entitled "Why do the trends in reactivity not apply for francium?" may be helpful.
    • Ivan Neretin
      Ivan Neretin over 3 years
      For chemical purposes, francium pretty much does not exist.
  • Micelle
    Micelle over 3 years
    Sorry for the bad English, it's my second language.