5
votes
1answer
67 views

Electronic model with highest prediction rate

Among many models, including the valence bond model (VB) or the molecular orbital (MO) model, which are the ones with best predictive power? (e.g. the MO is thought to predict spectroscopic ...
6
votes
3answers
150 views

Do filled Orbitals also hybridize?

Recently I was watching a video on Valence Bond Theory, on the MIT Open-Course youtube channel. The teacher there said that for hybridization to occur, electron promotion from fully filled orbitals to ...
5
votes
0answers
57 views
+50

When is it true that more nodes equals higher energy?

Consider all the MOs of some isolated molecule. (It could be a single atom too; I'll use MO to refer to AOs as well.) Number them in increasing order of the number of nodes (node = surface where the ...
4
votes
1answer
64 views

Why Aren't Chlorides Of The Noble Gases As Prevalent As Their Fluorides?

I can't find the answer to this question on this SE website, and I apologize for the repetition if it has been answered before. It is my understanding that compound formation has only been observed ...
5
votes
2answers
76 views

Counting Nodal Planes in cyclopropane

The energy of molecule orbitals increases with more nodal planes. W1 (in the attached picture) has no nodal plane. I'd like to know how to draw the nodal planes in cyclopropane molecule orbitals but ...
5
votes
0answers
61 views

What is the origin of the differences between the MO schemes of O2 and N2?

Here are the MO schemes of $\ce{N2}$ (left) and $\ce{O2}$ (right). Why is the $\sigma$-MO formed by the $p$ AOs energetically above the $\pi$-MO for $\ce{N2}$ but not for $\ce{O2}$? Can it be ...
3
votes
3answers
72 views

Why is the bond angle H-P-H smaller than H-N-H?

$\ce{N}$ & $\ce{P}$ are along the same group. $\ce{NH3}$ and $\ce{PH3}$ have one lone pair and both the central atoms are $\ce{sp^3}$ hybridized. But inspite of that, the former's bond angle is ...
1
vote
2answers
50 views

Molecular orbitals and “generalized” aufbau principle for heteronuclear molecular configurations

Is there any general ordering or rule for heteronuclear molecules like $\ce{AX_2}$, $\ce{AX_{n}}$, and their molecular bonding/antibonding configurations ($\sigma/\pi$ orbitals) accordingly to some ...
1
vote
2answers
100 views

Difference between backbonding and hyperconjugation and conjugation [closed]

What is the difference between backbonding and hyperconjugation and conjugation? I mean the basic differences as all are concerned with donation of electrons. What is the most striking effect of each ...
0
votes
0answers
19 views

Argon chemistry, molecular geometry and hybridisation

Can Argon hybridize orbitals and/or form covalent-like/ionic-like compounds? Is there any study of that?I would be happy to read concrete references... What kind of molecular geometries for argon ...
3
votes
3answers
104 views

PI Bonding in Carbon Dioxide

I am fairly sure the first diagram I drew for carbon dioxide is wrong in terms of showing pi bonding. This is because we use a pi orbital twice, which isn't possible. The second diagram corrects this ...
3
votes
1answer
38 views

Fourth principle of Molecular Orbitals

The fourth principle of Molecular Orbitals state that: Molecular orbitals are best formed when composed of Atomic orbitals of like energies. I'm not sure about ...
3
votes
2answers
203 views

Why does cyclopropane give bromine water test?

This question was in my exam and all I could tell was that it is related to high angle strain as the angle is $60^\circ$ in stead of required $109.5^\circ$. No book I have read mentions this. Also, ...
2
votes
2answers
57 views

Can a s orbital overlap with any p orbital to form a sigma bond?

In internet resources, only $p_z$ orbitals are shown to overlap with $s$ orbitals to form sigma bond. But my teacher says that according to Valence Bond Theory, $s$ orbital overlaps with all three ...
8
votes
0answers
106 views

Hyperlithiated Carbon Species

Below is replicated Question 1 from the Final Qualifying Exam of the Australian Chemistry Olympiad, 2004B, here. Question: The theory of promotion-hybridization is quite successful at explaining why ...
2
votes
1answer
68 views

Why is the 8-electron rule more important than the 2- or 18-electron rule

Why is the fulfilled electronic configuration of only $p$ orbital is stable. I mean why $II-B $ group with fulfilled $d$ orbital,$II-A$ group with fulfilled $s$ orbital...are not stable. Why makes ...
10
votes
4answers
256 views

Bond Length of CO+ is expected to be more than CO but it is found to be less. Why is this so?

According to Molecular Orbital Theory(MOT), the bond order of CO is 3. When CO+ is formed, bond order decreases to 2.5 and thus bond length should increase. However, the bond length of CO+ is found to ...
1
vote
2answers
85 views

Structure of NO2 compound?

What is the correct structure for the NO2 compound (not ion)? I always thought it was like: since the negative charge would be residing the on the highly electronegative oxygen, but was reading ...
2
votes
2answers
98 views

A molecule absorbs light having a specific wavelength, why doesn't it absorb shorter wavelengths?

I am currently studying computational chemistry and I am trying to understand the UV-VIS absorption of molecules. I know that UV-VIS absorption is electronic excitation and requires a specific energy. ...
0
votes
0answers
37 views

Constructing a MH6 MO diagram

I'm wondering how I'd construct an MO diagram for a MH6 complex, M is transition metal and the complex is a linear edge-sharing octahedra chain. This is with a view to potentially constructing a band ...
3
votes
1answer
42 views

Symmetry of an in-phase and an out-of-phase wavefunction “approaching” each other in an MO

Hiho. I have a question concerning this image (Chemistry, Catherine E. Housecroft et al., Pearson Education, 2010). In the text, it states the following: "Each of the new molecular ...
2
votes
1answer
61 views

Solution containing Iodine

The question is:- Iodine dissolves in a variety of solvents forming solutions that are purple, brown or any intermediate shade. This property is due to:- Hydrolysis of iodine ...
2
votes
2answers
92 views

Symmetry element in the coversion of cyclopent-2-enyl anion to pentadienyl anion?

I'm trying to draw the state correlation diagram for the reaction of cyclopent-2-enyl anion to pentadienyl anion but I don't know which symmetry element is preserved in this reaction. What could it ...
2
votes
2answers
118 views

Where does the 9th electron go in a $\ce{N=O}$ bond?

In the first resonating structure you can see 5 unpaired electrons and 4 shared electrons on nitrogen, then isn't this a extended octet? If it is so, then in which orbital that 9th electron is ...
1
vote
1answer
83 views

Which d-orbitals split according to CFT?

According to CFT, the degenerate d-orbitals split into $eg$ and $t_2 g$ groups. Are these the outermost nd orbitals which are vacant(4-d in case of 4th period) or the penultimate filled (n-1)d ...
3
votes
1answer
104 views

Bonding and nodes with molecular orbitals

If there is more overlap of the same sign wave function, this apparently leads to less energy. However, I don't understand why. My professor said that there would be less nodes, and less nodes means ...
1
vote
2answers
223 views

How does electron localization/delocalization work?

I can't find a simplified explanation on this topic. My textbook just adds to the confusion and all I'm really left with are more questions rather than answers. And adding to that question, does ...
0
votes
1answer
269 views

How can the Bonding in IF7 be explained using LCAO method?

I know that the VSEPR theory explains $IF_7$ (iodine heptafluoride)'s structure as a pentagonal bipyramidal one.The valence bond theory can be used to say that it has $sp^3d^3$ hybridisation(i think ...
1
vote
1answer
163 views

Molecular Orbital Diagram question

The molecular orbital diagram for $\ce{O2}$ says that the sigma 2p bonding molecular orbital is lower in energy than the pi 2p bonding molecular orbital. Why is this not the case in the $\ce{B2}$ MO ...
2
votes
2answers
248 views

LCAO (Linear Combination of Atomic Orbitals) and Phases

So when combining atomic orbitals to form molecular orbitals, you can either add the wave functions or subtract them. But at the same time, orbitals can exist in opposite phases (say one lobe of the p ...
7
votes
1answer
191 views

What utility does the Tau bond model of orbital overlap have?

In his book on molecular orbital theory, Molecular Orbitals and Organic Chemical Reactions, Ian Fleming notes that Pauling formulated an early alternative model to Huckel theory for explaining the ...
3
votes
2answers
411 views

Predicting molecular geometry from a formula

Can someone explain the following types of molecules and predict their structure and shape? It will help my understanding if you could provide an example. ...
5
votes
1answer
620 views

Resonance structure and hybridisation

I was given the first structure, and then drew the other 5 resonance structures. First of all, are they correct? ChemBioDraw had some complaints, but as far as I can see there's the same amount of ...
3
votes
1answer
242 views

Energies of atomic orbitals on molecular orbital diagrams

When we plot molecular orbital diagrams we use a linear combination of atomic orbitals. Where can I find the energies of particular atomic orbitals? In the picture below, the energies of 2s and 2p ...
2
votes
2answers
94 views

How does expansion of electron shells work?

How does it work? I've read that its about the similarity of the energy levels of $3d$ and $3p$, but shouldn't the electron shell $4s$ be filled before $3d$ if filled? So what is done with the $3d$? ...
5
votes
2answers
375 views

Bonding and anti-bonding orbitals in the light of time-dependent Schrödinger equation?

In organic chemistry, people draw 2p orbitals like this: and then they explain how the orbitals combine to non-bonding (π*) or bonding (π) molecular orbitals, like this: depending on whether the ...
4
votes
2answers
377 views

Why are these molecular orbitals invalid for hexatriene?

Here are the MOs (more accurately, the breakdown of the MOs) for conjugated hexatriene: Now, when first asked to draw the MOs myself, I drew this one for $\psi_3$: It still has two nodes, and is ...
7
votes
5answers
1k views

Carbon with 5 bonds?

I've heard that, even though according to Molecular Orbital Theory there is no chance of having nobel gases bonded to each other, it is not totally impossible. For example, under extreme conditions, ...
4
votes
1answer
228 views

Help understanding localized bonding theory

So I understand molecular orbitals and how to do VSEPR models, but I seem to be struggling with understanding localized bonding theory and how to do hybridizations. After drawing the initial lewis ...
6
votes
1answer
193 views

Molecular and Atomic Orbitals and Antibonding

When two atomic orbitals make one molecular orbital there must be an antibonding orbital also. Why should they make also an antibonding molecular orbital.
9
votes
5answers
2k views

What is the chemical structure of H₂SO₄?

I was looking at the chemical structure of H2SO4. Intuitively, I would have expected this molecule to be square planar in a p2d2 or sp2d geometry but rather, it is shown to be in an tetrahedral ...
8
votes
4answers
212 views

Hierarchy of electronic wavefunctions

The previous question contained too much unnecessary information and was edited. I am wondering about the "hierarchy" of wavefunctions. If one can combine atomic orbitals (AO) into molecular orbitals ...
4
votes
1answer
661 views

MO-Scheme of SCN- and its bonding properties when used as a ligand

I tried to figure out the MO-scheme of the tetragonal-bipyramidal complex trans-$\ce{[Co(en)2(NCS)2]SCN}$ in which the isothiocyanate ligands are bound to the $\ce{Co^3+}$-Ion in $\eta^{1}$-mode (en = ...
24
votes
2answers
2k views

Bonding in C2, a carbon-carbon quadruple bond?

Carbon is well known to form single, double, and triple C-C bonds in compounds. There is a recent report (2012) that carbon forms a quadruple bond in diatomic carbon, $\ce{C2}$. The excerpt below is ...
7
votes
1answer
135 views

Is the Springborg 6D phase space model used in modern molecular orbital modeling?

In a series of papers in the early 1980s, Michael Springborg explored an interpretation of the Wigner phase space function as an electron density in a six-dimensional $(q,p)$ phase space. He applied ...
4
votes
1answer
337 views

Why is the benzyne triple bond distorted?

In many places I've seen the "extra" bond in benzyne being labelled as $sp^2-sp^2$ overlap or distorted (not parallel) $p\pi-p\pi$ overlap. But I've failed to see why we can't have a normal, parallel ...