Which compound is more ionic?

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Karina Patel 1N
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Which compound is more ionic?

Postby Karina Patel 1N » Tue Nov 11, 2014 12:15 pm

For Fall midterm 2011, question 6B asks which compund is more ionic: LiH or HCl? I thought that by looking at the electronegativity of each atom, the difference between H and Cl is larger than Li and H, making HCl more ionic?

The answer to this problem is LiH. Could someone explain how you get this answer?

Thank you.
Karina Patel

Brandon Ganjineh 3F
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Re: Which compound is more ionic?

Postby Brandon Ganjineh 3F » Tue Nov 11, 2014 1:37 pm

Hydrogen has an electronegativity of 2.2. Chlorine has an electronegativity of 3.16. Lithium has an electronegativity of 0.78.

HCl's difference in electronegativity is Cl - H (3.16-2.2), which is 0.96.

LiH's difference in electronegativity is H - Li, since H is more electronegative in this case, (2.2 - 0.78), which is 1.42.

LiH has a larger difference than HCl, making it more ionic.

Chem_Mod
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Re: Which compound is more ionic?

Postby Chem_Mod » Tue Nov 11, 2014 2:23 pm

Yeah, the electronegativity difference is higher between Li and H rather than H and Cl, making LiH more ionic

rachaeld_1D
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Re: Which compound is more ionic?

Postby rachaeld_1D » Tue Nov 11, 2014 7:00 pm

How would we know that LiH is more ionic than HCl if we didn't have the electronegativity of these elements memorized? H and Cl is farther away on the period table than H and Li.

Kelvy Mansfield 1H
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Re: Which compound is more ionic?

Postby Kelvy Mansfield 1H » Wed Nov 12, 2014 11:23 am

You can tell that LiH is more ionic than HCl due to the fact that LiH is an actual ionic bond in the first place. Ionic bonds are those between a metal (lithium) and a nonmetal (hydrogen). The bonding between H and Cl is covalent bonding, so the fact that the bond between Li and H is actually ionic should let you know that LiH is more ionic.

The same goes for the next part of that question, where it asks if MgCl2 or PCl3 is more ionic. MgCl2 is more ionic since the bonding between magnesium (a metal) and chloride (a nonmetal) is ionic.

Quynh Nguyen 2O
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Re: Which compound is more ionic?

Postby Quynh Nguyen 2O » Sun Nov 16, 2014 6:00 pm

LiH is more ionic than HCl because H's electronegativity is 2.1, Cl has a electronegativity of 3.0, and Li's electronegativity is 1.0. There is a bigger difference from 2.1 to 1.0 than 3.0 to 2.1. The electronegativity trend on the period table doesn't work in this case because H has the same electronegativity as P. This wasn't mentioned in class, but you should get familiar with the element's electronegativity.

This periodic table shows that H has the same electronegativity as P. The electronegativity trend (increases from left to right and decreases top to bottom) doesn't always work, unfortunately.
http://www.thecatalyst.org/electabl.html

Andrew Knapp 1A
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Re: Which compound is more ionic?

Postby Andrew Knapp 1A » Fri Oct 02, 2015 2:23 pm

Is it possible for a compound to be "more ionic" than another, or is it just that some ionic bonds are stronger than others?

Erin Murashige 1L
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Re: Which compound is more ionic?

Postby Erin Murashige 1L » Fri Oct 09, 2015 2:09 am

A compound would be more ionic/have a stronger bond compared to another based on the electronegativity difference between the elements. I think in most cases it can be worded either way.


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