Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Joules23 on January 05, 2008, 07:13:23 PM
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I dont see how i am getting these incorrect..
XeCl4
Elec Geometry: Octahedral
Molec shape: Square Planar
So bond angles are:
90 and 180? .. This is coming up as incorrect
ICl3
EG: Trigonal Bypyramid
MS: T-shaped
Bond angles: 90, <90, 180
TeF4
EG: Trigonal Bypyramid
MS: Seesaw
Bond angles: 90, <90, 120, <120, 180
These are the Options:
90°
< 90°
109.5°
< 109.5°
120°
< 120°
180°
< 180°
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Bond angles are angles between three atoms. First try to figure out how many bond angles you need to determine for XeCl4, ICl3 and TeF4
EDIT
EG and MS is correct, though I don't know the meaning of seesaw, but I guess that stands for a distorted tetrahedron, doesn't it?
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Electronic Geometry: Octahedral-Correct
Molecular Geometry: Square Planar-Correct
The bond angles between the ligands and central atom are 90 degrees.
Bonding Pairs e-: 4
Lone Pairs of e-: 2
Hhybridization: sp3d2
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EDIT
EG and MS is correct, though I don't know the meaning of seesaw, but I guess that stands for a distorted tetrahedron, doesn't it?
Yes, same thing
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Electronic Geometry: Octahedral-Correct
Molecular Geometry: Square Planar-Correct
The bond angles between the ligands and central atom are 90 degrees.
Bonding Pairs e-: 4
Lone Pairs of e-: 2
Hhybridization: sp3d2
Thanks!... my teacher gave me a table, and it lists 90 and 180 as the angles.. but the answer that comes up correct is just 90.. Myabe the 180 is the lone-pair degree?
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For ICl3
The lone pairs would push the two outside Cl's inward toward the center Cl, right? it would be less than 90 degrees for those.. and 180 degrees from the top
<90 & 180.. right?
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WOO HOO You are right....!!!!!!
ICl3
Trigonal Bipyramidal-Electronic Geometry
T-Shaped-Molecular Geometry
Bonding Pairs of e-: 3
Lone Pairs of e-: 2
Hydridization: sp3d
And you are 100% correct-bond angles 90 and 180....
GOOD JOB!!!!!!!!!!!!!!!!!!!!!!!!! On your way to being a Quantum Chemist
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ROFL.. Thanks!!!!!!! ... btw do you have some type of software/wesbite thats telling you this.. and care to share?
Also is it 90, or <90 ?
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I am a Quantum Chemist this is my area of expertise-did my thesis on bonding using DFT...and I showed some very important results for Cobalt Tetracarbonyl complexes....
Here is a site that will help you...just the basics...but helps http://courses.ma.org/sciences/Hicks/APChemistry/APChemReadNotes/apchemreadch10.htm
Cotton and Wilkinson: Advanced Inorganic Chemistry-he died this year was at TAMU
Shriver,Atkins, and Freeman: Inorganic Chemistry
The TAMU site has tons and tons and tons of study and lecture notes. All their courses are televised locally and anyone can watch them at home. Dr. Brown started all that. try typing in transition metal bonding TAMU and see what you get....
And I can get you tons more...
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A molecular shape that results when there are 3 bonds and 2 lone pairs around the central atom in the molecule. The atoms bonded to the central atom lie at the ends of a "T" with 90° angles between them. ICl3 has a T-shaped molecular geometry.
VSEPR Theory
Predicts the spatial arrangement of atoms in molecules and polyatomic ions
Accounts for the geometric arrangements of electron pairs around a central atom in terms of the repulsion between electron pairs
Regions of high electron density (RHED)
The repulsion between electrons, is caused by two types of electron pairs:
Bonding Electrons
Electrons which are shared between 2 atoms
Lone Pairs
Electrons not involved in a bond
So your angles are 90 degrees. Due to the lone oair repulsions they are actually <90 degrees (see below and attached picture). Taking the lone pair repusions into account the bond angled for T-Shaped AB3U2 molecule are actually 87.5 degrees.
ICL3:
AB3U2
Examples: BrF3, ClF3, ICl3
Molecular Geometry-T-shaped
Electronic Geometry-Trigonal Bipyramidal
All molecules are polar due to lone pairs on the central atom
The See-Saw and T-Shaped geometries are both variations of the TBP (trional Bipyramidal) geometry. The lone pairs always occupy equatorial positions. Equatorial pairs have fewer 90° repulsions, and thus are at lower potential energy.
An example of this is PCl5 wher you can see that the axial bond lengths are longer. The greater repulsion of these lone pairs distort (bend) the both the axial and equatorial Cl atoms slightly away, to the opposite side of the molecule.
For ICl3 the T-Shape is distorted and the bond angles between the axial and equitorial ligands are 87.5 degrees so they are <90 degrees.
I have attached a picture that should help you see this.
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wow, thanks for all the info... i entered <90 and 180.. but incorrect. just <90 also incorrect.. and ran outta attempts :( .. Maybe the answer was <90 and <180 ??
What about TeF4
<90, <120 & <180 ?
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OK let s make sure we are talking about the right molecule.....do you mean the XeCl4 or do you mean the iCL3?
If it is the ICl3....you have a pic right there and all the bond angles are explained....Let me know If I have missed something or misunderstood....and this is TBP an AR3U2...The a is the central atom te I the B are the 3 bonded Cls and the U2 are the 2 unshared lone pairs....
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For the one that i got incorrect, i was talking about the ICl3
Input attempted for ICl3:
<90, 180 ..wrong
<90 .. wrong
and im assuming the correct answer was <90, <180 ?
My other question was for TeF4
are these the correct bond angles..
<90, <120 , <180 ?
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[...]...for ICl3: im assuming the correct answer was <90, <180 ?[...]
That's correct. You have two different angles ClaxICleq < 90° and ClaxIClax < 180°
My other question was for TeF4
are these the correct bond angles..
<90, <120 , <180 ?
Are there really three angles to be determined?
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Are there really three angles to be determined?
I guess only two?... But looking at SF4, which should have the same bond angles as TeF4 (right?).. im gettin mixed signals
http://iweb.tntech.edu/chem101-tf/graphics_AX5.htm (http://iweb.tntech.edu/chem101-tf/graphics_AX5.htm)
Shows 101.4 and 86.5
http://www.uwplatt.edu/~sundin/114/plsf4.htm
shows 90 and 120
http://cnx.org/content/m12594/latest/
shows 173 and 101.5
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I am conused too...OK we did the XeCl4....we know all that is done....the ICl3 is completed and that is done...so now stuck with the TeF4....OK I am just not following the statements "I put these in and they are wrong"
What is wrong...because ICl3 is <90
so are you sayin g the XeCl4 is stll wrong???? andf you need help wit TeF4????
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Yes XeCl4 is completed
Yes, ICl3 is completed.. but i got it wrong because the answer is <90 and <180.... I was allowed only two attempts, and i put: <90 and 180
just <90
Now im stuck on TeF4
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I guess only two?... But looking at SF4, which should have the same bond angles as TeF4 (right?).. im gettin mixed signals
SF4 and TeF4 are both distorted tetrahedral, but that doesn't mean they have the same bond angles.
You are right: there are three angles (my fault) FeqSFeq, FaxSFax and FaxSFeq
Why do you think there should be an angle <120° in consideration of the possible answers. (Example: Of course an angle <90° is also <120°, but <120° is wrong when the angle is < 90°, you know what I mean)
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OK ICl3 is correct.
XeCl4
Octahedral EG
Square Planar MG
The TeF4
TPB EG
SeeSaw MG
OK use the same ezact logic
SF4 and TeF4 are the same
Electronic Geometry : TBP
Molecular Geometry: See-Saw
sp3d bond angles: 120, 160
YES distortion due to equitorial lone pair repulsion: so angles are 177 and 104
Attaching picture
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Just made this in Paint.. this is what i think
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Is TeF4 AB4E2?
(Perhaps you call it AR4U2, same thing anyway)
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But what about this angle...
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OK so you have an AB4E2...or AB4 U2...same thing...you can clearly see the see-saw structure in the pic...the one done in paint...and that is definitly a distorted tetrahedral....
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OK so you have an AB4E2...or AB4 U2...same thing...
No. It's not AB4E2
Just made this in Paint.. this is what i think
This one I forgot when I was asking you "Are there really three...."
This is the FaxTeFeq angle. Value?
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Look at your central atom Te...what group is it in? Isn't it in the same group as sulfur....so what is the structure?
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That is what I am trying to say...he has the wrong formula...AB4U...is the ormula...that is what is wrong with his pic....but you can still see the seesaw even though his geometry is wrong....nNOT DEFINTLY NOT AB4E2...it is AB4E
or AB4U...that is the correct formula
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Your picture in PAINT represents OCTAHEDRAL geometry with two equitorial lone pairs...that is incorrect for your Te central atom..
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...or AB4U...that is the correct formula
Then we are agreed :)
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How about this.. and what about that angle in your pic i edited
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YES...OK let me restate comparison I was making...look at his paint pic....you can see the see-saw in there (have to skew the view) but he has way too many pairs of e-....supposed to give hints and not solve....I try that does not always work...and I thing with regard to geometry...picture is worth 1000 words...
Sorry about the confusion
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OK now you are rockin...SWEET
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@TeF4pic2.GIF
<180° ok, <90° ok
<120° don't think this is correct, as there is a possibility to answer "<109.5°"
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In TeF4, only one of the hybrid dsp3 orbitals is occupied by a lone pair. This structure may be represented by TeF4E, where E represents a lone pair of electrons. This is identical to SF4. This is a see-saw..
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@Alpha-Omega
I know what you mean. We're talking about the same. :)
It's like a TBP-system where one ligand is replaced with a lonepair, so the angle has to be <120°. In reality it is about 101°, so I am not sure about the correct answer.
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OK so here is another opinion:
In TeF4 one of the electron pairs is not involved in bonding (lone pair).
VSEPR theory predicts that a lone pair will repel bond pairs more than bond pairs repel bond pairs.
So the bonds will be pushed slightly out of shape, changing the angles to 179 degrees and 103 degrees respectively.
It is difficult to predict these angles precisely but you can guess.
So 3 sets of numbers all very close but the issue is <180 and <120 so regardless of the actual we are in the ballpark.
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I agree
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Cotton and Wilkinson: Advanced Inorganic Chemistry
May I just say. I own this book. It was my first Inorganic Chemistry book. It is the worst Chemistry book I have ever seen. I only keep it to point out to people how horrible it is. It is technically correct. It is just one of the most painful science books I have ever read.
Carry on.
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Well, I am sorry you disliked it so much. It is the academic/industry standard. Cotton is "the God of Inorganic Chemistry." I will never forget the day when my co-thesis advsor Dr Dhar received notification from Cotton that his work on LGOs had been accepted and approved...that made his life complete.
LOL when I went to TAMU for my weekend visit...(you go on those when you pick a grad school)...Dhar grilled me or an hour on my meeting with Cotton....he wanted to know every detail...Cotton was no longer taking grad students at the time...Personally, I ound him to be rather arrogant....BUT HE EARNED HIS ARROGANCE....
Perhaps you would find the Atkins text more understandable. There is another text by Huey that is pretty decent.
Additionally, Cotton has a Introduction to Inorganic Chemistry text....
Books have different appeal to different people. Most of the people I went to school with undergrad dreaded Inorganic Chemistry...they found Coottons book "difficult."
It is very common to use multiple texts when studing any subject in chemistry....go to the library and look at a few...there is bound to be one there that appeals to you.
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Ohh, I have tons of Inorganic books. And it is perfectly understandable. It is just painful to read.
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LOL...yes it can be very painful...but it has its rewards...and I guarantee you if you stick with it YOU WILL BE A STAR in grad school....you will never have so many people ask you FOR HELP IN YOUR ENTIRE LIFE....and ther is an old expressio: "younever really know your subject matter until you can teach it." So it has its rewards.
This is my favorite EXPRESSION/Joke:
This is organic chemistry:
C, H, O, sometimes a little N alkane, alkenes, alkynes, and aromatics: visualize the bonds: (single, double, triple, and a benzene ring)
As Dahr used to say: "The rest of the Periodic Table belongs to us."