All Questions
Tagged with molecular-orbital-theory molecular-structure
60 questions
1
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0
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29
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What is the difference between a 3c-4e bond vs 2 covalent bonds?
A 3c-4e bond is a bond in which 4 electrons are shared between 3 centers, but 2 covalent bonds between 3 atoms is also the sharing of 4 electrons between 3 centers (according to MOT)? Where is the ...
-1
votes
1
answer
27
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Hybridisation/bonding of XRn oxides
PH3 has a bond angle of around 93o, suggesting the s orbital has a minor role in the bonding, with the p orbitals in p-s σ bonding contributing to the orthogonality of the bonds according to Drago’s ...
3
votes
1
answer
180
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How to make the energy level diagram of dichlorodiammineplatinum(II)?
The oxidation state of platinum in $\ce{[PtCl2(NH3)2]}$ complex is $+2,$ so its configuration will be $\ce{5d^8 6s^0 6p^0}$ and the shape will be square planar.
But this complex has two strong field ...
- 43
-2
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1
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68
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I need a good 3d drawing of ferropericlase [closed]
I'm not a scientist, I'm an artist and I need a good 3d drawing of ferropericlase, where can I find that?
Thank you!
Niki
-2
votes
1
answer
133
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Why does the two OH bonds in H2O have different bond disassociation enthalpies? How does the bond cleavage happen here?
I came across this question, and in the text it was written as 'change in the chemical environment'. I wasn't satisfied with this explanation, so I am looking for a more detailed answer on this matter ...
1
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1
answer
100
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Does I2 form coordinate covalent bond with PI3 in PI3.I2 (PI5)
As PI5 is uncertainly stated as the combination of PI3 and I2. There are suggestions that phosphorus donates its 3s electron pair to molecular orbital of I2 or I2 donates its electron to 3d orbital of ...
- 651
-3
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1
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90
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According to molecular orbital theory, is the antibonding orbital empy when electrons are found in the bonding orbital?
According to molecular theory when 2 atomic orbitals combine, 2 molecular orbitals will be created. So if the electrons are in the bonding orbital will the antibonding orbital exist and just be empy? ...
2
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0
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229
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Why is the imine (C=N) bond so weak?
Nitrogen is similar to carbon in terms of electronegativity and size. MO theory suggests that the more electronegative N would result in a lowering of the of the π-bonding energy, E(πCN), below the E(...
- 21
1
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0
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59
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Reproducing Hydrogen Molecule Hamiltonian in OpenFermion
I am learning quantum chemistry at the moment and I'm trying to understand the Hamiltonian generated by the OpenFermion package. I'm now stuck at understanding how openfermion calculates the ...
- 11
4
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1
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284
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Self Consistent Field method and LCAO
I am reading about the Self Consistent Field Method and Linear Combination of Atomic Orbitals.
Suppose we have one electron and one nucleus, then we can solve the Schrodinger equation explicitly.
If ...
- 43
1
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53
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Is there a molecular orbital equivalent of rehybridization?
I generally have seen the pyramidal inversion of NH3 explained in terms of rehybridization. The sp3 hybridized NH3 changes to sp2, with the lone pair in the p orbital, and then reverts to sp3 in the ...
- 335
9
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2
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753
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Bonding in hypervalent molecules
I don't know where they go the electrons of the extended-valence in molecules like $\ce{SF6}$ or $\ce{PCl5}$ for instance because my teacher said that the d orbitals can't interact with s and p (or ...
- 691
1
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2
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440
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Why are there FOUR $sp^3$ hybridized orbitals in methane?
(This may be a stupid question, but I've only learnt about hybridization yesterday.)
I will take the example of methane.
The valence shell electron configuration of ground state of carbon is $2s^2 2p^...
- 531
2
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0
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38
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How do the spin-matrices change in systems without spherical symmetry?
The (non-relativistic) spin matrices of a free electron, with $z$ as the quantization axis, read:
$$
\boldsymbol{S}_{x}=\frac{\hbar}{2}\left[\begin{array}{ll}
0 & 1 \\
1 & 0
\end{array}\right],...
- 181
4
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1
answer
146
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Contribution, and the way thereof, of the core 6p orbitals of compounds of plutonium(VIII)
According to the NIST database, the ground-state configuration of plutonium(VIII) is [Hg]5f³6p³, when intuitively it should be the same as neutral radon([Hg]6p⁶). Since plutonium(VIII) compounds are ...
- 725
4
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1
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328
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In the LCAO method for $H_2^+$, why do we only add or subtract orbitals but never alter one of the phases of the orbitals?
TLDR:
Atkins' physical chemistry contains the quote "In general, from N atomic orbitals we can build N molecular orbitals". In the case of $H^+_2$, we use a combination of N=2 orbitals to ...
- 251
2
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0
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93
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Molecular orbitals energy under pressure
Suppose we have a hydrogen molecule $\ce{H2}.$ At room temperature the average distance of the nuclei is $r_0$ (without applying pressure).
If we put $n$ hydrogen molecules in a box with volume $V_\...
- 203
1
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0
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75
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Relation between the number of hybridised orbitals and the number of sigma bonds
March's Advanced Organic Chemistry (8th Ed.), has in its first chapter several tantalizing statements of the following variety;
Boron has only three valence electrons available to form bonds, hence ...
- 1,142
0
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0
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161
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Molecular Orbital Diagram
Chemists have revealed that $1 \lambda^{2}, 2 \lambda^{2}$ -disilene $\left(\mathrm{Si}_{2}\right)$ is diamagnetic while disulfur $\left(\mathrm{S}_{2}\right)$ is paramagnetic $(\mathrm{S}=1)$. Draw ...
- 117
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102
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Why does dilithium have a longer bond length than dihydrogen?
I've tried MO theory however they both have a bond order of 1. Which means we can not relate the bond order to the bond length.
My thinking -
I think that the h2 bond length is shorter due to only ...
- 9
1
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1
answer
508
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Comparing O−O bond length in hydrogen peroxide and dioxide(2−) ion
Problem
How can we qualitatively compare the bond lengths between $\ce{H2O2}$ and $\ce{O2^2-}?$
Answer
Attempt
I tried using molecular orbital theory, but since both have peroxide $\ce{O2^2-},$ the ...
- 583
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1
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227
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Energy levels of combined orbitals
I saw the MO diagram for a NH3 molecule but couldn't understand why the combined atomic orbitals were in the positions they were, and if these positions were fixed.
Why is the sigma anti bonding ...
- 748
0
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1
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79
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Forcing atoms closer together [closed]
Is there a method in chemistry to alter the energy of atomic bonds by forcing atoms closer together in a smaller volume?
Similar to how pressure squeezes atoms closer together.
- 119
4
votes
1
answer
2k
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Book Recommendation for Molecular Orbital Theory [duplicate]
I posting my question here since I have seen similar questions but I haven't found the specific answer I am searching for. I am seeking textbook recommendations on Molecular Orbital Theory with ...
- 167
2
votes
1
answer
6k
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What is the structure of CF3 radical? [duplicate]
In the class, I was told that $\ce{H3C^.}$ has a trigonal planar structure with the unpaired electron in $\mathrm{2p_z}$ orbital. But $\ce{H3C -}$ has a trigonal pyramidal structure.
But why does ...
- 185
2
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0
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96
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Can one describe the bonding of Na to F in terms of molecular orbital theory? What about valence bond theory?
I would kindly appreciate an explanation in terms of the two accepted quantum mechanical theories -valence bond & molecular orbitals- for the electronic energy level structure in natrium fluoride $...
- 217
1
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0
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378
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Breaking bonds with magnetic fields
I was wondering if we could break a bond by applying a big magnetic field on a molecule. The magnetic would just cause the spin of cores of the atoms making the molecule to be aligned , raising the ...
- 123
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1
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84
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Molecular antibonding orbitals energy
When we heat hydrogen the energy of the molecular orbital of H2(1s) is increased .What happens to the energy of the antibonding molecular energy of hydrogen(1s*)?
- 123
4
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482
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What exactly are the frontier orbitals in diradical species like O2?
I read about frontier orbitals, namely HOMO, LUMO. But what's exactly HOMO/LUMO? I know HOMO stands for highest occupied molecular orbital and LUMO stands for lowest unoccupied molecular orbital.
But ...
- 1,350
4
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1
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3k
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Geometry of Ni(acac)2
The complex $\ce{Ni(acac)2}$ is paramagnetic as expected , i.e it has two unpaired electrons giving rise to a magnetic moment of $ \sqrt{8}$ BM but doesn't have the tetrahedral geometry consistent ...
- 497
-1
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1
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106
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Question about d-orbitals [closed]
I saw somewhere that, "in PF5, the 3d orbitals of phosphorus end up in the anti-bonding molecular orbitals, and thus contribute less to the final molecule" and that "the hypervalency of some ...
1
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0
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63
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Calculating the Molecular Orbitals of a Molecular State [closed]
I am performing ab initio calculations on a heteronuclear diatomic compound using the MRCI method on the MOLPRO quantum chemistry package. I obtained the molecular states of the compound but I was ...
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2
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0
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63
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Finding out more stable conformer via molecular orbital interaction
Out of these two, which one is more stable? I'm unable to imagine the orientation of the lone pairs of O and ABMO of C and Cl bond.
Any tips to tackle these kind of problems?
- 203
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2
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828
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Is fluorine also hybridised in carbon tetrafluoride?
I had read that when an atom forms multiple bonds, it hybridises it's orbitals to minimise the repulsion and decrease the overall energy. But do the terminal atoms also exist in hybridised form?
E.g. ...
- 111
3
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1
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1k
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What is the explanation of the structure of H2XeO4?
Using the obsolete VSEPR theory I had a hard time predicting the structure of $\ce{H2XeO4}$. So I looked it up. I found the molecule via chemapps.stolaf.edu:
It looks weird to me. I can't explain the ...
- 195
-2
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2
answers
1k
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Why is manganate ion paramagnetic [closed]
When I tried to figure out why manganate ion is paramagnetic, given that its oxidation number is +6, I am not able to understand why there are unpaired electrons. Is it the case that six of the seven ...
- 9
5
votes
1
answer
91
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Mixing of molecular orbitals in polyatomic molecules
I am trying to solve the following Hamiltonian,$$H=-\frac{1}{2}\nabla^{2}-\sum_{i=1}^{10}\frac{1}{|\vec{r}-\vec{R_{i}}|}$$ Here $Z=1$ . To get all ther molecular orbitals of this system. I took the ...
- 419
2
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0
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137
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Theory of symmetry breaking in water?
As we all know $\ce{H2O}$ is bent ($C_\mathrm{2v}$) in its ground state equilibrium structure, rather than linear ($D_\mathrm{\infty h}$), which can be readily understood e.g. from the MO diagram of ...
2
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0
answers
503
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Structure of (CH3COO)3Fe
I'm a grade 12 student trying to comprehend MOT & LFT in Co-ordination compounds.
For one of our salt analysis(practicals), the test for acetate ion includes the addition of Neutral Ferric ...
- 21
-3
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1
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260
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Is 1-(1-Methyl cyclopropyl) carbocation [1] as stable as Cyclopropyl Methyl Carbocation[2]
Does the extra Methyl group interfere with the exceptional stability of Cyclopropyl Methyl Carbocation?
- 334
1
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1
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958
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Would an (NH3)2+ molecule be trigonal planar like BH3 rather than trigonal pyramidal?
I've been learning about using MO theory to explain why $\ce{BH3}$ and $\ce{NH3}$ have different geometries and by following the line of reasoning used to rationalise the differences in geometry I ...
- 115
2
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0
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330
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Which natural orbitals are better for CASSCF calculations for organic diradicals?
I am trying to perform CASSCF calculations for a series of diradicals. As input orbitals I have used two types of natural orbitals. One is unrestricted natural orbitals and the other MP2-based natural ...
- 81
1
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0
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289
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Why must the ground state of hydrogen molecule be gerade?
As we know, the electronic ground state of hydrogen molecule is $\Sigma_g^+$. My question is, how do we know it from the theoretical perspective?
The nuclear potential in the hamiltonian of hydrogen ...
- 111
1
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0
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3k
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How does the dx2-y2 orbital bond with four ligands in square planar metal-metal complexes
I understand that the complex [Re2Cl8]2- has a bond order of 4 between the ruthenium ions. The bond comprises of sigma interactions between
Dz2 orbitals, two sets of pi interactions between dxz and d ...
5
votes
1
answer
1k
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Does Bent's Rule only apply to molecules where there is hybridisation?
I would just like to ask if the pre-requisite for using Bent's Rule is that the bonding in the molecule involves hybridised orbitals.
I was thinking of why the bond angle in hydrogen sulfide (~ 92 ...
- 10.8k
1
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0
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2k
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two questions about character tables
I have learnt about group theory before I learnt MO theory, so I have a mathematical understanding of those orthogonality theorems and character tables.
I will use the character table of $D_{4h}$ to ...
- 303
8
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3
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3k
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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 ...
- 343
7
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1
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644
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Molecular Hamiltonian of Helium hydride ion
Currently, I am going through Quantum Simulation of Helium Hydride Cation in a Solid-State Spin Register. I am not a chemist but rather a computer scientist hence having trouble following the paper.
...
- 245
8
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1
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2k
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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 ...
- 375
7
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1
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11k
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Lone pairs in MO theory?
I have learned that non-bonding MOs are lone pairs. However when considering the MO diagram for the $O_2$ molecule, I do not see any non bonding orbitals yet there are two lone pairs on each oxygen ...
- 1,717