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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8
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1answer
36k views

Why an asymmetric geometry with sp3d and sp3d3 hybridization?

A molecule in which the central atom is $sp^3d^2$ hybridized ($\ce{SF_6}$), for example, acquires an octahedral shape, which can be explained by assuming that the hybrid orbitals arrange themselves to ...
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1answer
12k views

Why are the axial bonds of PF5 longer than those of the equatorial bonds? (Hybridization) [duplicate]

The axial bonds of $\ce{PF5}$ are longer than those of the equatorial positions. One explanation is that because the axial bonds are experiencing more repulsion than those of the equatorial and ...
7
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1answer
2k views

What is the highest possible expanded octet?

Often called "hypervalent", chemicals like phosphorous pentachloride and sulfur hexafluoride are possible due to the fact that their central atoms form covalent bonds with more than four other atoms, ...
2
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1answer
847 views

Order of priority in hybridization of d-orbitals

During hybridization of d-orbitals why the $d_{z^2}$ and $d_{x^2-y^2}$ orbitals are used up before the $d_{xy}$, $d_{yz}$ and $d_{zx}$ ?
5
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1answer
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What properties of an element determines the maximum number of bonds it can make?

From my conjecture, I think it's a mix between valence electron and the principal energy state, but I'm not sure. For example, C, N, O and F can only make a maximum of four bonds, as they can only ...
13
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1answer
9k views

Delocalization of π-electrons in nitrate ion

Benzene and nitrate ion are given in my textbook as examples for the delocalization of π-electrons. Benzene, due to symmetry of its resonating structures, is simple enough. We assume that σ-electrons ...
1
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1answer
765 views

How to find the possible valence states of elements in the lower end of the d block and the f block?

For silver, why don't the electrons in the 4d orbital move to the 5p orbital? Is it possible for any elements to move their electrons between $n$d and $(n+1)$p orbitals? When the f orbital is ...
2
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2answers
1k views

How to find the valence of transition elements?

Let's take Iron for example As we can see there are 4 desolate electrons in normal state. Can you tell me which electron moves to make the valence 2 and then 3. We have learnt to find the valence ...
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3answers
13k views

How can I derive the preferred oxidation states of a transition metal from its electronic configuration?

For example $\ce{Fe}\ (Z=26)$ Short formula: $\mathrm{1s^2\ 2s^2p^6\ 3s^2p^6d^6\ 4s^2}$. If we make the electronic formula we get 4 single electrons ($s=1/2$), which means that the valence in normal ...
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1answer
2k views

Determine the bond angle in a compound [closed]

How can we find the bond angle between 3 atoms in a compound? Please specify an equation which can be used for all compounds.
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1answer
59 views

Why V can't have the valence 7 by taking an electron from the 3p orbital and putting it into 3d?

Does that happen because 3p already has a bond?
8
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1answer
38k views

What holds atoms together? [duplicate]

I know atoms are held together by Ionic and Covalent bonds and i understand the ionically bonded atoms are held together by electrostatic forces. What about covalent bonds? How are molecules of bonded ...
64
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1answer
9k views

Why does F replace the axial bond in PCl5?

Why does $\ce{F}$ replace an axial bond in $\ce{PCl5}$? I realize that it would be more stable there than at equatorial bond, but what is the reason of its stability? Similarly in $\ce{AB4}$ type of ...
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0answers
112 views

Explanation of Bent's Rule [duplicate]

Why does the %s character increase on the orbital with electropositive atom? I do not seem to properly grasp this concept. Is this rule based on observation or is there any proof to it? If there is a ...
2
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1answer
2k 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 ...
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3answers
2k views

What is charge shift bonding?

Can someone explain to me charge shift bonding? I recognize that it is proposed as another domain of bonding - one different from ionic and covalent bonding. I am also told that $\ce{C-F}$ exhibits ...
19
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3answers
7k views

Why is one lobe of an sp3 hybridized orbital smaller than its other half?

A hybrid sp3 orbital is drawn with one lobe smaller than its other half, the latter which is of equal size when drawing the p orbital. Why is it so?
89
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2answers
35k views

What is Bent's rule?

I'm all bent out of shape trying to figure out what Bent's rule means. I have several formulations of it, and the most common formulation is also the hardest to understand. Atomic s character ...
11
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2answers
30k 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 ...
3
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2answers
886 views

Why is it O-Cl-O and not O-O-Cl?

I'm currently preparing my exam and while I did never think about this question during the course, it begins to confuse me right now... Why is it the structure of $\ce {ClO_{2}-}$ like $\ce {O-Cl-O}$ ...
5
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2answers
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Why do unbonded electrons exist in pairs?

Basically the term which we use to refer them is lone pair. In Lewis structure why we represent those unbonded electron in pairs. Like here (structure of SO2) Here if we assume both the unbonded ...
6
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1answer
185 views

Electronic model with highest prediction rate

Amongst 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 ...
13
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3answers
5k 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 ...
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1answer
585 views

2p Orbital Occupancy

What does the question mean by how many electron pairs are in 2p orbitals? How does one tell? Given that both the oxygen and the nitrogen are $\ce{sp^2}$ hybridized, wouldn't there be two 2p orbitals?
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2answers
733 views

Resonance - Legal Moves

My teacher insists that we can push electrons either from a bond to an atom's valence, or vice versa. Bond to lone pair; lone pair to bond, he insists. However, what about bond to bond? Is there a ...
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1answer
379 views

Orbital Electronegativity Considerations in Resonance Structures

After consulting three organic chemistry texts (Wade, Klein, and Brown), only one actually clearly delineates a few guidelines for picking the most significant resonance structure. The others mention ...
4
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2answers
4k 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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0answers
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Why does C=C bond replace C-O bond when two graphite platelets are rubbed against each other edge on edge?

When two small 2D carbon platelets are pushed into proximity, why do they release the edge attached molecule (maybe O) and then bond C to C? I think the answer I seek would address the relative ...
2
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3answers
23k views

Why does Pb normally have an oxidation number of +2?

Why does $\ce{Pb}$ have an oxidation number of $2^{+}$ while carbon and other elements in the same group have an oxidation number of $4^{+}$? Furthermore, why doesn't carbon also have a $2^{+}$ ...
4
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1answer
3k views

How does CrF₆³⁻ hybridize?

My textbook says that $\ce{[CrF6]^{3-}}$ is an example of $sp^3d^2$ hybridization. But I don't really see how. Chromium has an electronic configuration of: $$3d: \boxed{\uparrow}\boxed{\uparrow}\...
176
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8answers
156k views

Can an atom have more than 8 valence electrons? If not, why is 8 the limit?

According to some chemistry textbooks, the maximum number of valence electrons for an atom is 8, but the reason for this is not explained. So, can an atom have more than 8 valence electrons? If ...

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