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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Winga on December 03, 2004, 09:59:24 PM

Title: About Lewis Base!
Post by: Winga on December 03, 2004, 09:59:24 PM
A question is that it asks which one is a better Lewis Base, C4- or Si4-?

I don't know how to answer it!
Title: Re:About Lewis Base!
Post by: Donaldson Tan on December 04, 2004, 03:54:50 PM
which of the two is more likely to loose electrons?

a lewis base is defined as an electron pair donor.
Title: Re:About Lewis Base!
Post by: Winga on December 04, 2004, 10:42:54 PM
Si^4- is larger in size, so the attraction between the nucleus and valence e-s is weaker and its e- cloud is more polarizable, therefore, Si^4- is easier to donate e-s.

But, to compare C^4- & Si^4- stability, C^4- should be more unstable than Si^4- because of its larger electron-electron repulsion.
If we compare the basicity of F- & I-, I- is not quite available to donate e- than F-, because I- is more stable than F-.

So, there seems to have 2 factors to explain this case, which one is dominant?