1) O2
2) N2
3) CO
4) Ar
5) Kr
The answer is Kr but why since noble gases aren't electronegative. Wouldn't it be CO since it's the most polar?
2) N2
3) CO
4) Ar
5) Kr
The answer is Kr but why since noble gases aren't electronegative. Wouldn't it be CO since it's the most polar?
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It is true that CO is the most polar, and you would certainly pick a polar molecule over a nonpolar molecule (or atom in this case) to have a higher melting point, boiling point, and solubility in water IF the two are nearly the same size.
But they aren't. A krypton atom has 36 electrons, which isn't a lot, but a carbon monoxide molecule has only 14. (The krypton atom is also bigger.) Though London dispersion forces are weaker in nature than dipolar forces, they can outweigh the dipolar forces if there are enough addtional electrons (and room to move). If you look it up, you'll find that Kr has melting and boiling points approximately 40 degrees Celsius higher than carbon monoxide does. Again, just as in the solubility in water, the relative number of electrons (and the corresponding strength of the London forces) is much greater for the krypton atoms.
But they aren't. A krypton atom has 36 electrons, which isn't a lot, but a carbon monoxide molecule has only 14. (The krypton atom is also bigger.) Though London dispersion forces are weaker in nature than dipolar forces, they can outweigh the dipolar forces if there are enough addtional electrons (and room to move). If you look it up, you'll find that Kr has melting and boiling points approximately 40 degrees Celsius higher than carbon monoxide does. Again, just as in the solubility in water, the relative number of electrons (and the corresponding strength of the London forces) is much greater for the krypton atoms.