Distinguish covalent and partially covalent chemical bonds

[vinhphysics]

I read some books which mention about covalent and partially covalent chemical bonds. However, I cannot distinguish between them. Who can help me?
Thank you very much!

 

[Borek]

The only purely covalent bonds I can think of are those in diatomic molecules of gases. In every other case electronegativity of the atoms is different and the bond has some ionic character and some covalent character.

Please note covalent/ionic classification is not precise - while there are obvious differences between bonds (compounds) on both ends of the scale, there is a continuum of intermediary states. Where we put the border between one type of the bond and other type of the bond is just a convention.

 

[DrClaude]

The only purely covalent bonds I can think of are those in diatomic molecules of gases.

Just to add a precision: that would be homonuclear diatomic molecules. You can add also other special cases like the CC bond in ethane, where the molecule is completely symmetric.

 

[Borek]

Just to add a precision: that would be homonuclear diatomic molecules.

Good point, thanks. That's what I had on mind, but the wording was lousy.

 

[DrDu]

Even homonuclear bonds have an ionic contribution, and it is not easy to quantify the respective portion of covalent vs. ionic bonding. One appealing methods is the Bader analysis of "atoms in molecules":
http://www.chemistry.mcmaster.ca/aim/