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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Why is LiCl a hypovalent covalent molecule?
In a few books and online sources, LiCl is given as an example for "Incomplete Octet of Central Atom" that is, hypovalent. I don't understand why LiCl has covalent properties due to both the ...
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What is the Coulson-Fischer method of Quantum Chemistry
Recently, after understanding how the Valence Bond theory and Molecular Orbital Theory are similar through the "Modern Valence Bond Theory", I stumbled upon the Coulson-Fischer method. This ...
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How do the Valence Bond Theory and Molecular Orbital Theory describe the same wavefunction
How do valence bond theory and molecular orbital theory describe the same wavefunction despite one having localized electrons in a bond overlap and one having wave superimposition forming delocalized ...
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Why is the C-Cl bond length in 4-chlorobenzaldehyde shorter than in chlorobenzene?
I understand that the -COH group in 4-chlorobenzaldehyde withdraws electron density from the benzene ring via the mesomeric (resonance) effect. This should, theoretically, reduce the electron density ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 (...
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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 ...
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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 ...
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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 ...
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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\;...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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. ...
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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?
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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 ...
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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 ...
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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}$ ...
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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 ...
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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?
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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 ...
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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 ...
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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 {...
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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. ...
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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 ...
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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}$ ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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}?$
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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,\,...
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