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.
185
questions
-1
votes
2answers
100 views
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 ...
6
votes
1answer
84 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 ...
2
votes
1answer
136 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 ...
-1
votes
1answer
55 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 ...
1
vote
1answer
78 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 ...
1
vote
0answers
43 views
Distribution of Valence Electrons [closed]
I'm fairly confused over just how electrons are distributed in a molecule according to the lewis structure. The octet rule states that atoms have a tendency to have 8 electrons in their valence shell. ...
0
votes
0answers
62 views
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. ...
0
votes
0answers
38 views
Does overlapping partial density of states indicate formation of chemical bond?
Does overlapping partial density of states of two adjacent atoms indicate formation of chemical bonds between the two atoms? The partial density of states here means the density of states of an ...
-5
votes
1answer
33 views
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?
0
votes
0answers
67 views
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 ...
0
votes
1answer
89 views
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 ...
1
vote
1answer
91 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 $\mathrm d_{z^2}–\mathrm d_{z^2}$ ...
0
votes
1answer
374 views
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 ...
0
votes
0answers
33 views
Which forms the stronger sigma bond- s-s overlap or p-p overlap? [duplicate]
I'm asking this question as I hear arguments for either.
For s-s bond being stronger, I was told that because both are spherical, overlap can occur in any plane- a lack of directionality gives more ...
7
votes
1answer
262 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?
3
votes
0answers
73 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 ...
1
vote
0answers
98 views
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 ...
4
votes
1answer
192 views
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 $\ce {...
2
votes
0answers
100 views
Application of statement: extent of overlapping is always less than 50% because of electronic repulsion [closed]
Question from the online class:
Can two s-orbitals overlap as shown?
Dotted circles in diagram depict maximum probability region of s-orbitals in ideal situation when atoms A and B are not bonded. ...
3
votes
2answers
467 views
Explain on the basis of valence bond theory that tetracyanonickelate(II) ion with square planar structure is diamagnetic
Answers on the internet suggest that tetracyanonickelate ($\ce{([Ni(CN)4]^{2-}}$) with square planar structure is diamagnetic because $\ce{CN-}$ is a strong field ligand and causes pairing, but my ...
-2
votes
1answer
73 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 $\ce{sp^3d^3}$ ...
-1
votes
1answer
77 views
Why is it that nitrogen hybridizes in ammonia, yet in F2, fluorine does not [closed]
It seems rather arbitrary to me that we have decided that nitrogen sp3 hybridizes in ammonia to stay consistent with VSEPR, yet that fluorine uses its 2p orbital to bond with another fluorine in F2 (I....
-1
votes
2answers
55 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 ...
1
vote
1answer
101 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 ...
2
votes
0answers
34 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 ...
3
votes
2answers
242 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 ...
2
votes
0answers
46 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 ...
1
vote
0answers
38 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 ...
-1
votes
2answers
206 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 $\mathrm{sp^2s}?$
3
votes
1answer
316 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:
$$p_x+p_x,\,p_z+p_z,\,p_y+p_y,\,d_{zx}+p_x,\,d_{zy}+p_y,\,s+p_y,\,...
0
votes
2answers
101 views
Transition metals with closed shells
From wiki page about valence electrons:
An atom with a closed shell of valence electrons (corresponding to an
electron configuration $s^2p^6$ for main group elements or $d^{10}s^2p^6$ for
transition ...
2
votes
2answers
119 views
Insight into covalent bonds from electrostatic perspective
I try to understand, from the electromagnetic side only, how the molecule could be more stable than each atom, and concluded that it could not. Where is my mistake?
Here is an illustration :
By using ...
4
votes
0answers
130 views
Misconception in valence bond theory
Since the overlap increases with directional properties of orbital,
$$\ce{p - p > s - s > s - p}$$
However it is also observed that the bond strength of
$$\ce{H-F > H-H > F-F}$$
$$\ce{\{s ...
1
vote
0answers
284 views
Comparison between Molecular Orbital Theory and Valence Bond Theory
I have been reading about introductory Molecular Orbital Theory lately. Till now, I have used Valence Bond Theory to evaluate bonding. I have a few questions about it:-
In VBT, we used the idea that ...
0
votes
1answer
54 views
Why isn't just a fully occupied valence s orbital stable?
Why arent elements like calcium with an electron configuration of $[\text{noble gas}]\ n\mathrm{s}^2$ stable, although all the populated orbitals are fuully filled? Why is it necessary to obtain an ...
0
votes
1answer
1k views
Maximum number of coplanar atoms in difluorotrimethylphosphorane
In $\ce{PF2(CH3)3},$ what is the maximum number of atoms lying in one plane?
$\ce{P}$ is the central atom with the hybridization $\mathrm{sp^3d}.$ Two $\ce{F}$ atoms will form axial bonds with it, ...
3
votes
1answer
115 views
But what are anti-bonding pi-orbital? In search for an intuitive explanation [closed]
Imagine that you want to explain to an undergraduate why they have to to shade the pi-orbitals in a symmetrical way, i.e. dark on top (+), white on bottom (-) for two neighbouring pi-orbitals because ...
-1
votes
1answer
123 views
Is hypervalency a real thing? [duplicate]
I saw a proper debate going on between answers to a question about whether the octet rule could be violated. Some people were pointing to hypervalency in period 3 elements, due to the available d-...
1
vote
1answer
219 views
How to determine the shape of hybridized atomic orbitals in VB theory?
From diagrams, it's rather obvious how $sp$ orbitals are hybridized - the hybrids are just a composite of the $s$ and the $\pm p_{(x)}$ orbitals. However, $sp^2$ orbitals are not just composites of $s,...
0
votes
0answers
597 views
Hybridization state of oxygen in carbonyl sulfide (COS) [duplicate]
I've been scratching my head on this one for awhile here. In a carbonyl sulfide (COS) molecule, what is the hybridization state of oxygen?
Carbonyl sulfide is composed of a single carbon atom double ...
-1
votes
1answer
203 views
Backbonding in phosphorous pentoxide
I read this today in a book that $\ce{P=O}$ in $\ce{P4O10}$ consists of a coordinate bond and pπ-dπ backbonding, but why does this happen?
Can't phosphorus share its lone pair with one of the lone ...
2
votes
1answer
259 views
Why does this ligand form 6-coordinate complexes with Transition elements and 8-coordinate complexes with Inner transition elements? [closed]
The ligand given above shows different denticities with common transition and inner-transition metal ion i.e. 6 and 8.
The extra two denticities come from the two Nitrogen having 1 lone pair each. I ...
3
votes
2answers
799 views
Comparing bond angles in carbonyl dichloride and carbonyl dibromide
Background
I was studying VSEPR and hybridization theory and one of the popular questions in many textbooks was comparison of bond angle of $\ce{NH3}$, $\ce{NF3}$ and $\ce{NCl3}$.
$\ce{NF3}$ had ...
7
votes
2answers
227 views
Hypervalency of orthonitrate
I have always believed that it is impossible for the atoms of period 2 elements (when they are the central atoms in polyatomic ions/molecules) to accommodate more than 8 electrons in their valence ...
3
votes
3answers
218 views
Effect of magnetization on oxidation (rusting) of iron
Can magenetizing a piece of iron bar slow-down (or speed-up) the oxidation (rusting) process? In other words have any influence on it ?
From what I've looked up( wikipedia, quora), it appears that the ...
2
votes
0answers
52 views
Can one describe the bonding of Na to F in terms of molecular orbital theory? What about valence bond theory?
I would kindly appreciate an explanation in terms of the two accepted quantum mechanical theories -valence bond & molecular orbitals- for the electronic energy level structure in natrium fluoride $...
3
votes
1answer
910 views
Bonding and coordination of oxygen in a Ga2O3 crystal structure [duplicate]
I'm trying to find the crystal structure of gallium oxide ($\ce{Ga2O3}$). However, I find the images of the crystal structure in the peer-reviewed journals problematic.
First, I hop to the wikipedia ...
3
votes
0answers
69 views
(Mis)understanding on MOT
In VBT, one can understand the example of hydrogen like this - Two hydrogen atoms come closer to each other, and their orbitals overlap, stabilize, and ultimately result in a bond. This is not too ...
1
vote
0answers
40 views
Hybridization theory (orbitals used in different hybridizations)
Why is $d_{x²-y²}$ orbital used in $sp^3d$ (square pyramidal geometry) while $d_{z^2}$ orbital in $sp^3d$ (trigonal bipyramidal geometry)?
I came across this information while reading J.D.Lee Concise ...
1
vote
0answers
32 views
Reconciling electron configuration and valence electron distribution over separate energy levels in energy band theory [duplicate]
The electron configuration of a Silicon atom in its ground state is $\ce{1s^2 2s^2 2p^2 3s^2 3p^2}$, or equivalently, $\ce{[Ne] 3s^2 3p^2}$.
When looking at the energy-level scheme of a silicon atom, ...
