Hello

 

How can we explain that NR3 a stronger base is compared to PR3 (with R : alkyl group)?

 

How can we compare CF2, SiF2 und GeF2 concerning tehir stability and their structure?

 

Thank you very much.

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the strength of an acid or base, if you use the Lewis definition, is the molecule's ability to donate or attract electrons. Stronger bases are better electron donors, or in other words, the stronger bases have less ability to hang on to their electrons. Compare the electronegativity of nitrogen and phosphorus.

According to that explanation phosphines (P being less electronegative than N) would be more basic (less in control of their electrons) than the corresponding amines. Trivalent phosphorus isn't at all a hard base because its lone pair is in a far larger probability cloud than that of nitrogen. As a result, the orbitals don't align well and phosphines aren't good at deprotonating anything.

what does CF2 sif2 and get2 mean?

Carbon, Silicon and Germanium Fluorides.

It's a fair question; do those difluorides (of 4 valent elements) exist for any length of time?

I can imagine that they can exist for a long time if they are VERY VERY dilute. The same is true for hydroxyl. Astronomers have found clouds with a large percentage of hydroxyl, but these clouds still have a lower density than the best vacuum we can make on earth.

 

This kind of molecules are VERY reactive, but as long as they do not meet anything, they can exist.