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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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$2p$ promotion before hybridisation [closed]

Consider the process for $2p^3$ hybridisation $2s$ electron promotes to the $2p$ energy level. Now the single $2s$ electron and the $3$ $2p$ electrons combine to form $4$ hybrid $sp^3$orbitals, that ...
e2121's user avatar
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Why cant H2O be linear? [duplicate]

My understanding is that a H2O molecule cannot be linear due to repulsions between the electrons of the non-bonding domains and the hydrogen: However i was wondering why the structure could not take ...
Varshil MVH Pets's user avatar
2 votes
1 answer
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Where are the electrons located when two atomic orbitals overlap? (VBT)

According to the valence bond theory(VBT), a covalent bond is formed by the overlapping of atomic orbitals containing electrons of opposite spin which pair together. However what is the physical ...
Nothing's user avatar
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Stability comparison between Acetylene/Ethyne (C2H2) and Nitrogen Gas (N2) [closed]

N≡N is more stable than H2N—NH2 (hydrazine) But HC≡CH is less stable than H3C—CH3 Why is it so? Even though the size of the corresponding compounds and hybridization is the same? (Usually ethane is ...
Maddy's user avatar
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Is concept of weak and strong field ligands applicable in valence bond theory?

I study coordination chemistry at high school. I have read about valence bond theory (VBT) and crystal field theory (CFT) as well. My teacher taught me that VBT is based on the experimental values of ...
InfinityLies's user avatar
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2 answers
273 views

Do PH3F2 and XeS2 exist (in the light of hybridization and Valence Bond Theory)?

Do $\ce{PH3F2}$ and $\ce{XeS2}$ exist, in accordance with Valence Bond Theory? According to Drago's Rule, if the central atom of a compound is an element of the third period, and the attached atom has ...
Bongo Man's user avatar
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Why are different Aluminium valencies observed from NMR and what logic can be used to normalise molar ratios of different valency atoms?

Question 1: I've observed different chemical shifts in 27Al Nuclear Magnetic Resonance (NMR) spectra of commercial aqueous sodium aluminate, indicating the presence of both trivalent [Al(III)] and ...
Hendrix13's user avatar
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A water molecule is bent. Why? [duplicate]

Consider the bent shape of $\ce{H2O}$ with a bond angle of $104°$. From my understanding, this is due to the lone pair repulsion between the 2 pairs of lone pair electrons. Hence, it adopts a ...
Quin Gardiner Bax's user avatar
-2 votes
1 answer
73 views

Energy Levels in Bohr's Diagram

When drawing the Bohr Diagram of Potassium with 19 electrons, the valence electron goes in the fourth concentric circle, but third energy level can hold up to 18 electrons? Does it mean that ...
Diego's user avatar
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Formation of tetrafluoroborate using VBT and hybridisation

How can the formation of $\ce{BF_4^-}$(Boron is $\ce{sp^3}$ hybridized) be explained using VBT and Hybridization? So far, I understood that one electron from s orbital gets excited and jumps into a p ...
Mathlover12345's user avatar
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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 ...
Shira's user avatar
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Does chloride ion have its electron in hybrid orbitals? [closed]

Where are the electron valamce shell electron located in $\ce{Cl}^-$. Are they in pure $p$ and $s$ orbitals? Or are they in $sp^3$ hybrid orbital? If the answer is that they are in pure orbitals i.e. ...
Chesx's user avatar
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Explaining the low-lying electronic state of NO

The question asks the following: 'The molecule NO has a low-lying electronic state 0.015 eV above the ground electronic state. Explain why this is the case and state the electronic degeneracies of ...
Bartholomew696969's user avatar
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Im confused over sulfur's ability to form 4 bonds

I'm a High School AP Chemistry student, and I am still confused on sulfur. I understand why it can form $2$ bonds to complete its outer shell, but when I was drawing a Lewis structure for Thiosulfite (...
Nolan Kiplinger LN 10's user avatar
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1 answer
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How do you know if a bond according to VB theory consists of 2 "3 electron bonds" or one "fully paired" bond?

First of all, I want to discuss the whole thing strictly according to the VB - theory and not use any concepts of the MO - theory. According to Linus Pauling, the "3 electron Bond" is the ...
iwab's user avatar
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How can atoms get very close together even without direct covalent bonds between them? [closed]

Generally speaking, because of the Pauli exclusion principle, it’s difficult for the electron clouds of two atoms to overlap unless they are covalently bound together. The degree of overlap can be ...
哲煜黄's user avatar
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How do I determine the hybridization of terminal atoms? [duplicate]

I've read that terminal atoms do not undergo hybridization because there is no need to. For example, CF4, C undergo sp hybridization, but fluorine do not hybridize. How about CO2? Why is oxygen sp2 ...
Bryan Foong Zhi Chuan's user avatar
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3 answers
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Energy Conservation

So as we start Valence Bond Theory in Chemical Bonding from Inorganic Chemistry. Then we are introduced to reasoning behind bond formation as follows: As it is a well known fact that $$Potential\;...
Techno Freak's user avatar
2 votes
3 answers
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Why would a metal form an ionic compound with a nonmetal from a lower period?

Take sodium iodide for example. I understand both elements can obtain a full outer shell via the electron transfer. But doesn't the electron move from a lower-energy orbital ($3s$ in sodium) to a ...
Adam Herbst's user avatar
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Why is the 8N (octet) rule not applicable in the case of boron triflouride?

In my chemistry class we learned the so-called "8N rule" (very similar to the Octet rule) which helps one determine the number of bonding electron pairs and thus the number of bonds in ...
Hrach's user avatar
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How does the MO-LCAO theory explain the direction of valence bonds?

As all the bells sound, the common explanation of geometry of a molecule (consider the water molecule) is due to overlaping electron density. The valence bond theory of the water molecule describes ...
Sergio's user avatar
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Bonding in boron icosahedra [closed]

How do boron atoms make five bonds with other boron atoms even if the electron configuration of unbound boron atoms is [He]2s²2p¹, i.e. there is an insufficient number of outer electrons? Are the ...
Get_ Maths's user avatar
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2 answers
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Does the spin of electron in d half-filled d-orbital changes while forming low spin complex?

Recently I learned how VBT explains the formation of coordination complexes. But I am stuck at a point that seems hard to digest for me. Consider a metal ion having an electronic configuration as ...
Samyak Marathe's user avatar
6 votes
1 answer
155 views

How are the energies of natural atomic orbitals calculated when they are, strictly speaking, not "meaningful" wavefunctions?

There are several programs that can calculate the "energies" of the natural atomic orbitals(NAO) that come from NBO analysis. However, I have several evidence that, unlike the energies of ...
Kanghun Kim's user avatar
3 votes
1 answer
206 views

Justification for using valence bond theory and molecular orbital theory together?

Elementary gen chem books will make the careful distinction between the two theories and then proceed to claim that chemists can use both to complement each other to explain the behavior of certain ...
cheekylittleduck's user avatar
-1 votes
1 answer
130 views

What is the best way to visualize hybridization [closed]

I had learnt hybridization in various complex definitions some of them as "complex overlapping of orbitals (in quantum mechanical model) which leads in changing of shape of orbitals itself. But ...
Anomalous's user avatar
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1 answer
607 views

Why is the Br-C-H bond angle in CH3Br smaller than the Cl-C-H bond angle in CH3Cl?

Can someone explain for me why the Br-C-H bond angle in CH3Br is smaller than the Cl-C-H bond angle in CH3Cl? From what I know, F-C-H in CH3F has a smaller bond angle than Cl-C-H in CH3Cl because F is ...
ManhAu's user avatar
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Why is maximum number of covalent bonds 3? [duplicate]

In my textbook it is mentioned that maximum 3 covalent bonds can be formed within 2 atoms, which makes sense as 1 p orbital from each can be used for sigma bond and the remaining 2 can form pi bonds. ...
Zombie Killer's user avatar
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1 answer
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Manganese and valence layer [closed]

Why does manganese make $4$ bonds in $\ce{H_2MnO_4}$ when it has only two electrons in the valence shell?
Lambert macuse's user avatar
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Hybridisation of Azide ion

In azide ion, $\ce{N3-}$, the hybridisation is $\mathrm{sp}$ because number of hybrid orbitals = steric number, the central atom $(\ce{N})$ has 6 bonds with other $\ce{N}$ atom, 2 of which are sigma ...
Geonke's user avatar
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Role of 'p' Orbitals in Graphite Carbons

In the graphite arrangement of carbons, if we model them according to hybridization theory, the carbons in graphite are sp2 hybridized. This would mean that one s and two p orbitals hybridize, making ...
prado5083's user avatar
2 votes
1 answer
132 views

Comparing strengths of σ-bonds formed by $\mathrm d_{z^2}$ and $\mathrm p_z$ orbitals

According to my professor $\mathrm d_{z^2}–\mathrm d_{z^2}$ σ-bond is stronger than $\mathrm p_z–\mathrm p_z$ σ-bond as the extent of overlapping is greater in $\mathrm d_{z^2}–\mathrm d_{z^2}$ ...
Samardeep singh's user avatar
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1 answer
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Why does the Lewis structure for NH2 have 4 dots and not 3? [duplicate]

Nitrogen has 5 valence electrons. So I would expect that when bonding with two hydrogens, two electrons would go into those bonds, and three would remain in place on the nitrogen. Yet, all the ...
CodyBugstein's user avatar
7 votes
1 answer
506 views

How to compare magnetic moment of chromium(III) and cobalt(II) ions?

Is there any way of comparing the magnetic moments of $\ce{Co^2+}$ and $\ce{Cr^3+}$ gas phase ions by just going through their electronic configuration?Or is it just experimental data?
Bitthal Maheshwari's user avatar
3 votes
0 answers
100 views

Why is the bond angle of sulphur difluoride greater than that of hydrogen sulphide?

Why is the bond angle of $\ce{SF_2 (98.05^\circ) > SH_2 (92.11^\circ)}$? Isn't this contradicting Bent's rule or otherwise electron repulsion rule ? Fluorine is more electronegative and hence it ...
Ashish's user avatar
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1 vote
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How are 3 center-4 electron bonds any different from 2 center-2 electron bonds? [closed]

How are the bridge bonds in $\ce{Al2Cl6}$ different from the terminal bonds? We could have just mentioned the bridge bond formed by $\ce{Cl}$ as a coordinate bond. Why introduce this extra concept? I ...
Satya's user avatar
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4 votes
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Why does NH3 cause pairing in case of some metal complexes and doesn't in case of others?

I was met with a question that required me to find which complex is an outer orbital complex, and two of the options included $\ce{ [Ni(NH3)6]^2+}$ and $\ce{[Co(NH3)6]^3+}$, I want to know why $\ce {...
Ashwin Singh's user avatar
2 votes
0 answers
351 views

Application of statement: extent of overlapping is always less than 50% because of electronic repulsion [closed]

Question from the online class: Can two s-orbitals overlap as shown? Dotted circles in diagram depict maximum probability region of s-orbitals in ideal situation when atoms A and B are not bonded. ...
Jay's user avatar
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3 votes
2 answers
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Explain on the basis of valence bond theory that tetracyanonickelate(II) ion with square planar structure is diamagnetic

Answers on the internet suggest that tetracyanonickelate ($\ce{([Ni(CN)4]^{2-}}$) with square planar structure is diamagnetic because $\ce{CN-}$ is a strong field ligand and causes pairing, but my ...
Kumar Mayank's user avatar
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1 answer
212 views

Hybrid lobes of sp3d2 and sp3d3 [closed]

It's known that $\ce{sp^3d}$ hybridization has 5 lobes; 3 equatorial with $\ce{sp^2}$ lobes and 2 axial with $\ce{dp}$ lobes. Do we have such splitting in $\ce{sp^3d^2}$ and $\ce{sp^3d^3}$ ...
Tanmay Gajapati's user avatar
-1 votes
2 answers
145 views

do electrons in different orbitasl in a same subshell have same energy

In valence bond theory, I suppose that electrons in say, 2px and 2py have the same energy because of the same structure of orbitals. But what about 3dxy and 3dz^2? Do they also have the same energy? I ...
Habib's user avatar
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1 vote
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739 views

What is the difference between resonance and π conjugation

I have seen electron delocalization mentioned frequently in 2 separate contexts: resonance (ozone, carbonate / nitrate...) and π-conjugation systems (aromatic compounds). While the 2 initially sound ...
Vulgar Mechanick's user avatar
2 votes
0 answers
78 views

is there a stead fast rule to predict hybridization or is it just an ad hoc concept

Before I start of this question, Ι want to make it clear that I know that hybridization, like pretty much all of chemical bonding, are just made up to qualitatively rationalize observations. I know ...
Vulgar Mechanick's user avatar
3 votes
2 answers
1k views

Why does delocalization (only) occur in molecules represented by resonance hybrids?

Before I start this question, I am aware tha Electrons in all molecules are delocalized to some extent Delocalization is a the phenomenon and resonance is an attempt to explain it. When I asked this ...
Vulgar Mechanick's user avatar
2 votes
0 answers
118 views

what does "overlapping" of orbitals mean and why does it effect bond strength(VBT)?

according to valence bond theory, bonds are formed due to the pairing of unpaired valence electrons due to the overlap of half-filled orbitals, and the strength of the bond depends on the extent of ...
Vulgar Mechanick's user avatar
1 vote
0 answers
52 views

Direction of valence bond and Unsöld's theorem

Is it true that the atomic orbitals of separate atoms already have directionality, which ensures the directionality of the valence bond? Or another words, what is the real spatial distribution of the ...
Sergio's user avatar
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-1 votes
2 answers
217 views

Why there is no sp2s hybridization in hydrocarbons? [closed]

If carbon's $\mathrm{sp^2}$ orbital is overlapped with hydrogen's $\mathrm{s},$ then why it is $\mathrm{sp^2}$ and why not $\mathrm{sp^2s}?$
fariha's user avatar
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3 votes
1 answer
719 views

Which combinations of orbitals lead to pi bonds according to Valence Bond Theory?

How many of the following combination of the orbitals will lead to formation of $\pi$-bonds with $z$ axis being the internuclear axis: $$p_x+p_x,\,p_z+p_z,\,p_y+p_y,\,d_{zx}+p_x,\,d_{zy}+p_y,\,s+p_y,\,...
Kshitij Kumar's user avatar
1 vote
2 answers
300 views

Transition metals with closed shells

From wiki page about valence electrons: An atom with a closed shell of valence electrons (corresponding to an electron configuration $s^2p^6$ for main group elements or $d^{10}s^2p^6$ for transition ...
pasaba por aqui's user avatar
2 votes
2 answers
160 views

Insight into covalent bonds from electrostatic perspective

I try to understand, from the electromagnetic side only, how the molecule could be more stable than each atom, and concluded that it could not. Where is my mistake? Here is an illustration : By using ...
Mathieu Krisztian's user avatar

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