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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: xshadow on January 09, 2021, 06:17:43 PM

Title: CsI vs CsF stability
Post by: xshadow on January 09, 2021, 06:17:43 PM

Which one is the most stable?

I'v seen some datas:

melting point:  CsF > CsI
lattice energy:  CsF > CsI

hard soft interaction :  CsI compound is preferred because both ions are soft


Now  according to hard soft CsI is the favoured product....but according to the lattice energy and the melting point CsF should be the  most stable (better interaction between ions,more negative lattice energy)...so which one is the most stable?!
thanks

Title: Re: CsI vs CsF stability
Post by: chenbeier on January 13, 2021, 12:43:44 PM

Flouride has the highest electronegativity. Accept very strong 1 electron. Caesium (beside Francium) has the lowest one, it will donate very easy an electron. So the compound will be more stable. Also is Caesium a big ion and flouride a small one. Iodide is also a big one, what lowest the bonding force.

Title: Re: CsI vs CsF stability
Post by: xshadow on January 14, 2021, 05:55:11 AM

Quote from: chenbeier on January 13, 2021, 12:43:44 PM

Flouride has the highest electronegativity. Accept very strong 1 electron. Caesium (beside Francium) has the lowest one, it will donate very easy an electron. So the compound will be more stable. Also is Caesium a big ion and flouride a small one. Iodide is also a big one, what lowest the bonding force.

you are saying that CsF is more stable than CsI cause electronegativity of fluoride....ok

BUt why according the Hard-soft theory CsI will be predominant against CsF because in CsI we have two soft ions (softs-soft interaction are favourite against soft-hard like CsF)...is in contraddition with the argument of the electronegativity...

thanks