Tagged Questions

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0answers
21 views

Why nitrogen is inactive but oxygen is more active? [on hold]

Why is nitrogen, being the major component of the atmosphere, inactive but oxygen, the minor component, is most reactive? As per Le Chatelier's principle, if the concentration of a reactant is much ...
2
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1answer
28 views

Why hybridization occurs in diatomic molecule

In diatomic nitrogen There are two electron configurations I'd like to compare: 1s2 2s2(lone pair) 2p3(the bonding electrons sigma,pi,pi) 1s2 2sp(lone pair) 2sp(sigma bonding) 2p2(pi,pi bonding) ...
1
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1answer
91 views

C=O and C=C antibonding orbitals

Why is the pi star orbital of the C=C bond higher in energy than the antibonding pi orbital of the C=O bond? I thought it was the other way around; it's relatively easy to add something to a C=C ...
3
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0answers
43 views

Irreducible Representations to Classify Atomic Orbitals [duplicate]

I have some major confusion on Irreducible Representations. An example of a problem i have is Based on the character table for the point group of each of the follwing molecules, which irreducible ...
5
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1answer
118 views

What are t2g and eg in CFT?

In the Crystal Field Theory, when the splitting of the d-orbital occurs, it gets divided into two parts... The upper part with higher Energy is the $t_{2g}$ and the lower part with lower Energy is ...
5
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1answer
70 views

Diatomic halogens - bond strength

Why is the F-F bond relatively weak? And why does bond strength decrease from Cl-Cl to I-I? Does this have anything to do with "lone-pair" repulsions on the rather small F-F molecule? I haven't ...
3
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1answer
29 views

Structure of benzene

How does molecular orbital or valence bond theory explain the delocalised structure of benzene? I.e. when the carbon forms 3 bonds with other carbons/hydrogen, what happens to the remaining hybridised ...
0
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1answer
61 views

How do you determine how many electrons occupy the anti bonding orbitals?

For molecular orbital theory: How do you determine how many electrons occupy the anti bonding orbitals? Also, why does hydrogen gas have no anti bonding orbitals- if each atom's electrons form a ...
4
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1answer
67 views

Asymmetry in trigonal bipyramidal geometry

I teach an MCAT course in chemistry. I like to explain VSEPR by saying.. first, imagine arranging electron pairs around the central atom so they are maximally distant from each other, and uniformly ...
5
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1answer
158 views

Show the vibrational frequency of F2- is much lower than that of F2

Basically I need to draw the molecular orbital for $\ce{F2}$ and then answer a bunch of questions about it. I have drawn it correctly, as far as I know, but I don't know how to use it to show that the ...
6
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2answers
348 views

How does a Frost diagram reproduce the solutions to the wave equation?

I came across a Frost diagram for cyclic compounds in my book, and all my book had to offer was that it geometrically reproduces the solutions of the wave equation, and can therefore determine the ...
2
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1answer
27 views

Quick way to find magnetic nature of compounds or ions

According to the Molecular Orbital Theory, the method to check whether a given compound is paramagnetic or diamagnetic is to draw the molecular orbitals and then to see whether we have all the ...
3
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1answer
72 views

Unequal ionization energies of methane

Why does methane have two different ionization potentials? How does this work? I understand that MO theory predicts C-H bonds of differing strength, while hybridization predicts C-H bonds of varying ...
5
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1answer
102 views

What is the point of introducing virtual orbitals in Hartree-Fock calculations?

Let us for simplicity discuss RHF formalism. For $2n$-electron system we have $n$ Hartree-Fock equations written for $n$ spatial orbitals $\{ \phi_{k} \}_{k=1}^{n}$ $$ ...
2
votes
1answer
87 views

Which one, Mulliken charge distribution and NBO, is more reliable?

Sometimes the Mulliken and NBO turn out to be so different that I can't decide which one I can trust. I've heard that Mulliken is inaccurate, but is NBO always accurate? And should I use Gaussian or ...
0
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1answer
74 views

Nitric Oxide Dimerization

This is the molecular orbital diagram for nitric oxide: Now, we know that nitric oxide can dimerize. However, why does nitric oxide dimerize as to form an $\ce{N-N}$ bond? Why not an $\ce{O-O}$ ...
2
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1answer
64 views

Position of nodal planes in molecular orbitals

From the attached picture (MO diagram of cyclopentadienyl anion) I can figure out where the nodal planes are, but why are they exactly at these positions? Why is this nodal plane invalid?
3
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1answer
148 views

Energetic Placement of Atomic Orbitals in the HCl Molecular Orbital Diagram

How are the 3p orbitals of chlorine lower in energy than the 1s orbital of hydrogen?
3
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2answers
261 views

Why are least electronegative elements usually in center of lewis structure

Many sources state that one of the primary rules for molecular structures is that the least electronegative element is in the center. However, none of them explain why this is the case. Is this ...
5
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1answer
87 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
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3answers
226 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 ...
12
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1answer
299 views

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
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1answer
92 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 ...
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2answers
110 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
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1answer
138 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 ...
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3answers
349 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 ...
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1answer
62 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
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2answers
170 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
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0answers
33 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
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3answers
187 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
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1answer
44 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
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2answers
257 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
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2answers
67 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 ...
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1answer
156 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
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1answer
94 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
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4answers
773 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 ...
2
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2answers
121 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
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2answers
147 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
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0answers
60 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
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1answer
46 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
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1answer
70 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
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2answers
155 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
148 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
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1answer
89 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
124 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
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2answers
459 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 ...
1
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1answer
446 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 ...
2
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1answer
199 views

Why is there a difference between O2 and B2 sigma 2p molecular orbitals in diagrams?

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 ...
5
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3answers
348 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 ...
9
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2answers
231 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 ...