Understanding Bond Energies: X-Y Bond Energy Contribution

[guiromero]

Hello.

Could someone please help me with this question about bond energy from an MIT course:

"For two bonded atoms X and Y, a small X and large Y will result in a bond energy (E A-B) with a large __________ contribution."

Thanks a lot if someone can help.

 

[guiromero]

I've already gotten the answer, it's "ionic".

 

[Hyperfine]

Why is it ionic?

 

[guiromero]

I got this answer from another forum and the person said that these types of bonds have a high ionic character, which is the percentage of difference between the electronegativity of two covalently bonded atoms.

 

[Hyperfine]

Why would you expect the electronegativity of the respective atoms to depend upon the size of those atoms?

 

[guiromero]

Sorry, I forgot to correct the statement. The correct is like that:

"For two bonded atoms X and Y, a small eX and large eY will result in a bond energy (E A-B) with a large __________ contribution."

Where e = electronegativity