Which of these bonds is the most polar? The least polar?

Which of these bonds is the most polar? The least polar?

1. C-N
2. C-C
3. C-O

tell whether bond is ionic, polar covalent, or nonpolar covalent?

1. Br2
2. BrCl
3. HCl
4. SrF2
5. SiH4
6. CO
7. N2
8. CsCl

Answer:
The C-O bond is most polar, then C-N, and C-C least polar.

See:

http://en.wikipedia.org/wiki/electronega...

for a list of elements and their electronegativity.

Oxygen 3.44
Nitrogen 3.04
Carbon 2.25

Oxygen 3.44 - Carbon 2.25 = 1.19 most polar
Nitrogen 3.04 - Carbon 2.25 = 0.79
Carbon 2.25 - Carbon 2.25 = 0.00 least polar


*****************

Find the difference in electronegativity between both elements.

If difference less than 0.5, then nonpolar covalent.

If difference greater than 0.5 but less than 1.7, than covalent.

If difference greater than 1.7, than ionic.

For explanation of choosing 1.7 as breakpoint between covalent and ionic, see:

http://neon.chem.uidaho.edu/~honors/elec...


Br2 bond is nonpolar covalent.

Nonpolar covalent bond = "A bond in which electrons are shared between elements having a difference in electronegativity of less than 0.5."

Difference in electronegativity between bromine and bromine is zero.


BrCl bond is nonpolar covalent.

electronegativity of chlorine = 3.16
bromine = 2.96

The difference in electronegativity is 0.20 that is less than 0.5.


HCl bond is polar covalent.

electronegativity of chlorine = 3.16
hydrogen = 2.20

The difference in electronegativity is 0.96. Greater than 0.5 so cannot be nonpolar covalent, but less than 1.7 so not ionic.


SrF2 bond is ionic. Strontium is a metal, and the fluoride forms crystals. Metal / non-metal bonds are usually ionic.

Electronegativity of Fluorine = 3.98
Strontium = 0.95

The difference in electronegativity is 3.03, that is greater than 1.7, so ionic.


SiH4 (silane) bond is nonpolar covalent.

Electronegativity of silicon = 1.90
hydrogen = 2.20

The difference in electronegativity is 0.3 that is less than 0.5.


CO bond is polar covalent. Difference in electronegativity is 1.19, that is greater than 0.5, but less than 1.7.


N2 bond is nonpolar covalent. Difference in electronegativity is zero.


CsCl bond is ionic.

Electronegativity of cesium = 0.79
chlorine = 3.16

The difference in electronegativity is 2.37, that is greater than 1.7.
C-O bond is most polar due to maximum electronegativity difference btw two atoms.

Br2-npc
BrCl-pc
HCl-i
SrF2-i
SiH4-pc
CO-pc
N2-npc
CsCl-i

i-ionic,pc-polar covalent,npc-nonpolar covalent
I'm not going to give you the answer straight out.

I will tell you that the difference in electronegativities will tell you which is more polar. Don't want to look that up? Then learn your periodic table. Oxygen and other elements who can easily gain a few electrons (or less) to obtain an octet are highly electronegative. Elements who will give up electrons to gain an octet are not very electronegative at all and are usually on the left hand side of the periodic table.

Now, if a difference in electronegativity will tell you the polarity of the sample, how polar do you think a C - C bond would be? Not very since a Carbon is a carbon is a carbon right? That being said, how polar do you think a Br2 molecule would be?

I have faith in you. I think you can get through this minor problem using a good periodic table and that wonderful brain of yours!

The answers post by the user, for information only, FunQA.com does not guarantee the right.



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