Questions tagged [valence-bond-theory]
Questions about how the atomic orbitals of the dissociated atoms combine to give individual chemical bonds when a molecule is formed.
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Why is $1s-1s$ orbital overlapping stronger than $2p_x-2p_x$ orbital overlapping?
Assume the x-axis to be the internuclear axis. Hence, both $1s-1s$ and $2p_x-2p_x$ will form $\sigma$ bonds.
Also consider the fact that $p$ orbitals have more directional characteristics.
Given the ...
2
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0answers
30 views
Why is it not possible for seven close copper atoms to come together to gain a noble-gas configuration of valence electrons?
My textbook says the following about metallic bonding:
The metal copper has one valence electron. The valence electrons of nearby copper atoms are shared in a similar way to covalently bonded ...
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0answers
34 views
How to Choose Orbitals for Hybridization
Recently, I was reviewing my textbook regarding orbital hybridization, and one of the problems was to determine the hybridization of each of the atoms in $\text{CO}_2$. I understand why the ...
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1answer
31 views
Periodic Table and Atomic Radius
Well Wikipedia says that the atomic radius is lowered for elements in a group closer to noble gases (same row). It also says that those elements want to keep their valence electrons more than metals, ...
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1answer
35 views
Electric conductivity
Well I was wondering why some materials have a higher resistivity than others . So I took two elements randomly . I picked carbon and silicon . Carbon has lower resistivity than silicon and obviously ...
6
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1answer
233 views
Valence bond theory and molecular orbital theory — how do they complement one another?
Based on my readings, valence bond theory (VBT) and molecular orbital theory (MOT) tend to complement one another in explaining a molecule, but I don’t understand how VBT helps us explain the ...
2
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0answers
102 views
How do I explain these bond angles in SF4 and SOF4?
From here and here I found that the bond angle between the equatorial $\ce{F}$'s in $\ce{SF4}$ is less than that in $\ce{SOF4}$. I understand that is because of greater repulsion by lone pair than by ...
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1answer
153 views
Why does NH3 hybridize at all?
So in Chemistry class I've been taught that hybridization is a way we can explain things such as how $\ce{CH4}$, for example, forms four, equally strong bonds.
However at the same time I'm told that ...
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1answer
67 views
Why is a carbon to iodine pi-bond less stable than a carbon to fluorine pi-bond?
This question comes from a second semester undergraduate organic chemistry course. Please refer to the image below with regard to the question.
My understanding of the trend in section 4a is that "...
0
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1answer
94 views
Reason for shorter bond between sulphur and oxygen?
I recently came across this sentence in my textbook “the bonds between sulphur and oxygen in oxides of sulphur (SO2 and SO3 ) are much shorter than might be expected for a single bond”
SO3
I feel ...
2
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1answer
114 views
Why is carbon monoxide a monodentate ligand
Carbon monoxide has lone pairs on both the carbon and the oxygen atoms. However, I have never seen any complex where the oxygen atom or both the oxygen and the carbon atoms are the donors.
I know ...
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0answers
48 views
Dichlorine monoxide molecular geometry
I need to predict the geometry of Dichlorine monoxide, using the main link theory: Lewis model, VSEPR and hybridization of molecular orbitals.
First, the Lewis structure is a graphical representation ...
4
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1answer
812 views
Bonding in Zeise's salt
I am not sure I completely understand the bonding in coordination compounds formed by donation of pi electron cloud by the ligands to the central atom.
For example, consider Ziese's salt:
I came ...
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1answer
83 views
How many equal Xe–O bond length are present in (XeO_6)-3? [closed]
I tried to solve this problem by drawing a structure but the structure did not give me any answer and I was not able to draw the proper structure please help me out.
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0answers
19 views
Why does aluminum in zeolites form tetrahedras? [closed]
It forms a bond with four oxygen atoms even though it has only there electrons in his outter shell?
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1answer
66 views
Molecular Geometry [duplicate]
Why is it that for a molecule with trigonal bipyramidal geometry, the lone pair is located in the equatorial region whereas for a molecular with an octahedral geometry, the lone pair is located in the ...
1
vote
1answer
464 views
Graphite: Thermal and electrical conductivity
I recently encounter this question:
Compare, while providing an explanation, the thermal and electrical conductivity of graphite to that of diamond.
Provided answer:
Graphite conducts electricity(...
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0answers
144 views
The nature of Chemical Bonds [closed]
It was nearly a year ago when I appeared for my first interview through the KVPY (a research oriented scholarship exam) when one of the questions the panel asked me was :
What is a chemical bond?
...
4
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1answer
962 views
Ionization energy of C2-, C2, and C2+
My textbook says that $\ce{C_2}^-$ has a lower ionization energy than both $\ce{C_2}$ and $\ce{C_2}^+$. I calculated that the bond orders of $\ce{C_2}^+$, $\ce{C_2}$, and $\ce{C_2}^-$ are 1.5, 2, and ...
3
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0answers
252 views
Why is octet extra stable? [duplicate]
In chemistry, it is agreed in general that the octet is extremely stable, through experiments except in some cases. But is there any specific theoretical reasoning for that?
According to me, if:
...
0
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0answers
105 views
Why don't I get the same value of percentage ionic character of a particular molecule from different equations?
About the ionic character of a polar covalent compound Pauling gave two equations as
[1-$e^{.25(x_a - x_b)}] $%
[18$(x_a-x_b)^{1.4}$]%
Hanary and Smith gave the equation
[$16(x_a-x_b)+3.5(x_a-...
3
votes
1answer
59 views
Using real wave functions for chemical bond explanation
My question related with another one here.
For explanation valence bond direction chemists are used real wave functions, for example $p_x, p_y, p_z, \ldots$. But this functions do not describe the ...
3
votes
1answer
583 views
Why do halogens have odd numbers as oxidation number?
Halogens like $\ce{Cl}$ always exhibit $+7,+5,+3,+1,-1$ as their oxidation numbers. I found the following answer after checking several sources:
Halogen atoms have $7$ electrons in their valence ...
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1answer
380 views
Why is the oxidation state of Carbon (-4)?
Based on my understanding, atoms try to achieve the electronic configuration of the nearest noble gas, by losing or gaining electrons. For example, Sodium is closest to Neon, so loses an electron so ...
5
votes
1answer
550 views
Where do the lone pairs go in the “true” resonance structure?
Consider the "true" resonance structure of $\ce{CO3^2-}$:
The bottom diagram leaves out the 2 lone pairs, so 4 electrons disappeared in the bottom image as compared to the top one. Are these ...
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vote
1answer
548 views
Do 1s & 2s orbitals overlap of different atoms while forming sigma bond? I
Do 1s & 2s orbitals overlap of different atoms while forming sigma bond?
I think they should overlap as there will not be enough energy difference between them.
3
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1answer
294 views
Buckminsterfullerene double bonds [closed]
I am not now nor have I ever been a chemist.
I'm practicing by drawing molecules in the Chemspider structure search tool. Today I drew buckminsterfullerene, in order also to test my 3D spatial ...
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0answers
412 views
How to calculate steric number of methyl free radical?
According to the definition, steric number = number of atoms it is attached + lone pair.
In that way, I get 4 for methyl free radical which means sp3 hybridization . But that's wrong !
Why is this ...
8
votes
3answers
1k views
HCH bond angle in cyclopropane and cyclobutane
I understand why the $\ce{CCC}$ bond angles in cyclobutane and cyclopropane are less than ideal $109.5^\circ$ due to the geometric restrictions they encounter in a cyclic structure. However, it is not ...
2
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0answers
663 views
Why are d orbitals used in the hybridisation of PCl5 and similar compounds? [duplicate]
Phosphorus uses its $\ce{3s}$, three $\ce{3p}$ and one $\ce{3d}$ orbitals for its hybridization in $\ce{PCl5}$ and similar compounds.
However, shouldn't it use its $\ce{4s}$ rather than $\ce{3d}$ ...
4
votes
1answer
14k views
How can the hybridisation schemes of transition metal complexes be determined?
Lets say I have to find hybridisation of $\ce{[Ni(CO)_4]}$ and $\ce{[Ni(CN)_4]^{2-}}$.
The metal atom/ion in these compounds are $\rm Ni$ and $\rm Ni^{2+}$ respectively.
So the outer shell ...
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0answers
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The affect of effective nuclear charge on energy gap between subshells
A few days ago my teacher taught me about $\mathrm{d}$ orbital contraction. He said that in $\ce{SF6}$ the hybridization of sulphur is $\mathrm{sp^3d^2}$. He said that although the $\mathrm{d}$ ...
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1answer
281 views
Hybridisation and bond strength
I'm a high school student with minimal mathematical knowledge about the theory of chemical bond. (I just have a bit of theoretical background). I came across a statement which stated that "The more is ...
3
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3answers
5k views
Determining the structure of N2O using hybridization
I have learnt how to determine the structure of molecules where only the central atom is hybridised like $\ce{ClF3}$, $\ce{C2H2}$, $\ce{PCl5}$, but in $\ce{N2O}$ it seems as though both nitrogen and ...
3
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1answer
2k views
Valence Bond theory, VSEPR theory and predicting the shapes of the molecules
I read about the above mentioned theories then used them to predict the molecular geometry. However, I found that the shape/geometry of a molecule obtained from both the theories was same. For example,...
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0answers
33 views
How do delocalized π electrons satisfactorily fill π orbitals? [duplicate]
The above example is benzene.
Only six electrons contribute to the 6 π bonds and pπ orbitals. Normally, an orbital requires two electrons to satisfactorily "fill" it. I don't understand how this ...
6
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0answers
300 views
Chemical bonding with f orbitals
For the elements such as rhenium, osmium, iridium how probable is for electrons in the inner 4f orbitals to gain energy and take part in a molecular orbital (such as an $f^2 d^2 s p^3$ hybrid orbital) ...
3
votes
3answers
1k views
Inductive effect and bond strength
What is the relation between the inductive effect on bond length and strength.
how would one rank the bond strength of
$\ce{CH3-H}$, $\ce{CH3CH2-H}$, and $\ce{(CH3)2CH-H}$
I know that alkyl groups ...
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1answer
127 views
Ammonia sigma bonds p character
Why does ammonia's sigma bonds to H have more p character than let's say ethane.
I am guessing it has something to do with the effect the lone pair has on bond lengths and angles, but not quite sure ...
7
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1answer
645 views
How to explain molecular geometry without the help of VSEPR, valence bond, or hybridization theories?
I was taught, at the high school level, how to rationalise molecular geometries with the help of VSEPR, valence bond, and hybridization theories.
However, I have recently also come to know that these ...
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vote
2answers
428 views
Structure of AsF3Cl2
Since the molecule has 5 bonding pairs and zero lone pairs, the shape should be trigonal bipyramidal. But one thing i am confused about is which atom(s) will occupy the axial and the planar positions, ...
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votes
1answer
323 views
Confusion regarding sigma bond and pi bond
I was recently told that a sigma bond between two $\mathrm{3p}$ orbitals is possible but a $\pi$ bond between the same orbitals is not possible.
Although I was not told the reason, I am speculating ...
3
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1answer
565 views
Hybridisation and the Schrödinger equation
I am slightly confused about hybridisation and how it relates to molecular and atomic orbitals, despite having pored through many sources online. I was hoping someone could verify whether my current ...
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1answer
886 views
Ethylene hybridization [duplicate]
In the carbon atom, there are electrons in 2s, 2Px, 2Py, and 2Pz. Out of these orbitals, only 2Px, 2Py, and 2s are hybridized. The 2Pz orbital is left. When making a bond there is a pi bond between ...
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2answers
145 views
CO₂ molecule π bonds [closed]
Why does $\ce{CO2}$ make two π bonds? Why can't it make four σ bonds? Also, why do the π bonds not involve for repulsion?
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1answer
524 views
Has it been observed that the dihydrogen molecule dissociates into ions?
As we know from the improved methods valence bond theory (VB), as well as molecular orbital theory (MO-LCAO), the wave function of the $\ce{H2}$ molecule consist of two terms, which belong to covalent ...
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0answers
2k views
Why is the nitrile nitrogen sp hybridized?
This site, from which the above image was taken, indicates that the hybridization of the orbitals on the C and N atoms in hydrogen cyanide is sp. I can certainly see how that would be the case for ...
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2answers
4k views
What is the maximum covalency of oxygen?
My text says it to be 4. I believe it's 2. Is there any compound where covalency of 4 is observed?
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3answers
873 views
Do Li4 or Li8 molecules exist?
I've read that alkali metals form ionic bonds; $\ce{Li}$ is an exception which majorly forms covalent bonds. Wikipedia says dilithium exists. This makes me wonder why $\ce{Li_8}$ doesn't exist. It ...
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2answers
867 views
Which overlap is stronger, and why?
I was just wondering which overlap is stronger, 2s-3p or 3s-2p? I believe this can probably be explained by involving some sort of mathematics (?) which I haven't used yet.
Edit: Note that 2s-3p ...
