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DAT destroyer General Chem question number 101?

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dallaspage

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Q)Consider XeF2. What is the molecular shape and hybridization of the Xe?

I checked answer, the answer said that the fluorine are in the axial position , the lone electron pairs are equatorial.

I don't know this part is being said. And can you explain that drawing the Lewis structure of this molecule and linear shape and sp3d hybribization.

Thanks..
 

mmorris86

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spyder3292
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Q)Consider XeF2. What is the molecular shape and hybridization of the Xe?

I checked answer, the answer said that the fluorine are in the axial position , the lone electron pairs are equatorial.

I don't know this part is being said. And can you explain that drawing the Lewis structure of this molecule and linear shape and sp3d hybribization.

Thanks..

http://i41.photobucket.com/albums/e283/spyder3292/XeF2.jpg

Ok, I'm no chem major or anything but i'll take a shot at this... First you count the electrons, Xe is gonna have 8 and flourines each have 7 so 8+2(7)=22. The F will each consume 8 (2 in the bond to Xe and the rest as lone pairs because F is monovalent, meaning it only likes to share one pair of electrons in a single sigma bond) and then the Xe must take on the remaining 6 as 3 lone pairs(each lone pair is 2 electrons). This will give the effect of 5 "groups" attached to the Xe, requiring 5 spaces, or hybrid orbitals. That explains the sp3d hybridization; 5 spots s, p, p, p and d. Look at my pathetic drawing above that was done on paint... my chem-bio draw software license that i had from orgo lab expired :(

Because the 2 flourines are going to be pushed one up and one down (axial) giving a 180 degree bond angle between the two, they will appear linear to one another. And then the 3 lone pairs of electrons will be in the equitorial position, giving an overall shape of triagonal bipyramidal.

PS: When all of you chem people attack my post, please be kind... i wanted to feel better about gchem. DAT in 6 days lol
 
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nze82

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Q)Consider XeF2. What is the molecular shape and hybridization of the Xe?

I checked answer, the answer said that the fluorine are in the axial position , the lone electron pairs are equatorial.

I don't know this part is being said. And can you explain that drawing the Lewis structure of this molecule and linear shape and sp3d hybribization.

Thanks..
Here's how you draw the Lewis structure:
1-Choose the central atom (The most electronegative atom is generally the central atom)
2-Calculate the total # of electrons.
3-Calculate the # of lone pairs of electrons.
4-Put the lone pairs of electrons around the surrounding atoms. If you still have some lone pairs left, after completing the octet on the surrounding atoms, put the remaining lone pairs on the central atom.

Let's see how we can use the above steps to draw XeF2:

step#1: Xe is the most electronegative, so it's the central atom.
step#2: Xe = Group#8-->8 electrons F = Group#7-->7 electrons
Since there are 2 F atoms, then the total # of electrons equals:
8 + 2(7) = 22
step#3: To calculate the number of lone pairs, use the following formula:
(Total# electrons) - 2(#Lines attached to the central atom)
22 - 2(2) = 18
step#4: Out of these 18 lone pairs, 12 can be arranged around the two F atoms (6 around each). The remaining 6 must be arranged around Xe, to give the following (Check the attached file).
Anytime, you want to arrange 5 species (includes atoms and/or lone pairs) around a central atom, according the VESPER Theory, the molecular shape must be, Trigonal Bipyramidal and the central atom is sp3d (1s + 3p + 1d = 5 hybridized orbitals) hybridized:
vsprxef2.gif


 

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