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About the "Rough Guideline"

Posted: Wed Oct 19, 2016 9:20 pm
by Xin Huang 3E
About the rough guideline of differentiating the ionic bond and covalent bond, I am still a little confused about those electronegativity difference falls between 1.5 to 2, how we should figure out what types of bond there are. I was a little off on the class, so...I heard Dr. Lavelle mentioned how whether it dissolves in water can be a criterion (since...only molecules don't dissolve in water), but I missed the other criterions we could base on...

Re: About the "Rough Guideline"

Posted: Thu Oct 20, 2016 5:20 am
by Josephine_Tang_1N
Generally, I base it on how far away the elements are from each other on the periodic table: the farther they are i.e. opposite sides of the periodic table, the more ionic in character.

Re: About the "Rough Guideline"

Posted: Thu Oct 20, 2016 11:03 pm
by Xin Huang 3E
Sounds logical ^ ^. Thank you so much!

Re: About the "Rough Guideline"

Posted: Thu Oct 20, 2016 11:43 pm
by Chem_Mod
Hi there,

When the difference in electronegativity between two atoms is greater than 2.0 on the pauling scale, we typically refer to that bond as ionic.
Difference in electronegativity between 0.2-0.5 we consider generally to be nonpolar covalent, and 0.6-2.0 we would consider polar covalent

Re: About the "Rough Guideline"

Posted: Thu Oct 20, 2016 11:54 pm
by Chem_Mod
Chem_Mod wrote:Hi there,

When the difference in electronegativity between two atoms is greater than 2.0 on the pauling scale, we typically refer to that bond as ionic.
Difference in electronegativity between 0.2-0.5 we consider generally to be nonpolar covalent, and 0.6-2.0 we would consider polar covalent


As discussed in class any time two different atoms are covalently attached the electron density distribution is not symmetric.
Most chemists do not distinguish between an electronegativity difference of 0.5 vs 0.6.
In general most chemists refer to bonds as:
ionic
or
polar
or
non-polar (as in H2, O2, etc.)