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.

Filter by
Sorted by
Tagged with
-1
votes
1answer
31 views

Comparing strength of Sigma bond strength formed by orbitals

According to my professor $d_{z^2}-d_{z^2}$ sigma bond is stronger than $p_z-p_z$ sigma bond as the extent of overlapping is more in $d_{z^2}-d_{z^2}$ overlap, because of directional nature and of $...
-1
votes
0answers
71 views

Would uranium(XII) oxide be electron-deficient?

Uranium is six electrons ahead of radon and radon is six electrons ahead of mercury, so the uranium(XIII) cation, which is theoretically possible(see e.g. https://www.sciencedirect.com/science/...
-6
votes
0answers
25 views

Maximum covalency of sulphur

Why does sulphur stop at 6 bonds? Why can't it form 9 bonds because even after forming 6 bonds,it has empty d orbitals? And even if we consider steric factors, then why in the structure of sulphate ...
0
votes
1answer
32 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 ...
-2
votes
0answers
22 views

In WATER Oxygen have 2 lone pair then why it donates only 1 lone pair to metal ion in coordination compound [duplicate]

As Water is monodentate ligand and has 2 lone pair then why it donates one lone pair to metal ion as monodentate ligand are those which have one donor atom please help
0
votes
0answers
32 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
192 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?
19
votes
3answers
9k views

Why are pi bonds only formed when sigma bonds are formed?

While studying about bonding there was one statement that "pi bonds can only be formed only with sigma bonds" as we know that in double bond there is 1 sigma bond and 1 pi bond but then one question ...
3
votes
0answers
61 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
385 views

Hybridisation and bond strength

I'm a high school student with minimal mathematical knowledge about the theory of chemical bond. (I just have a bit of theoretical background). I came across a statement which stated that "The more is ...
1
vote
0answers
60 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 ...
13
votes
1answer
8k 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 ...
2
votes
0answers
84 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 does $\...
2
votes
0answers
68 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. ...
2
votes
2answers
332 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
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 ...
-2
votes
1answer
67 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 $\ce{sp^3d^3}$ ...
7
votes
2answers
185 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 ...
2
votes
1answer
7k views

What is the maximum covalency of oxygen?

My text says it to be 4. I believe it's 2. Is there any compound where covalency of 4 is observed?
-1
votes
1answer
70 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
48 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
64 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 ...
3
votes
2answers
136 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
29 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 ...
2
votes
2answers
112 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 ...
2
votes
0answers
32 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
34 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 ...
17
votes
1answer
11k views

How does VB theory explain the Si-O-Si bond angles in SiO2?

Silicon dioxide has a huge variety of structures. Most of them are built up from connected $\ce{SiO4}$ units — the $\ce{O–Si–O}$ angle is $109.5°$, accordingly. The VB/hybridization approach to this ...
-1
votes
2answers
202 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
164 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,\,...
1
vote
1answer
144 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
2answers
71 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 ...
4
votes
0answers
113 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 ...
3
votes
3answers
130 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 ...
64
votes
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 ...
1
vote
0answers
263 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 ...
5
votes
1answer
26k views

How can the hybridisation schemes of transition metal complexes be determined?

Lets say I have to find hybridisation of $\ce{[Ni(CO)_4]}$ and $\ce{[Ni(CN)_4]^{2-}}$. The metal atom/ion in these compounds are $\rm Ni$ and $\rm Ni^{2+}$ respectively. So the outer shell ...
0
votes
1answer
53 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
2answers
554 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 ...
3
votes
1answer
83 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
93 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
votes
1answer
12k views

Why does Sulfur have 12 valence electrons in the Sulfate ion? [duplicate]

So I am completely and utterly confused about why sulfur has $12$ valence electrons. I understand in it's configuration, it has $2$ electrons for the $3\mathrm s$ subshell, and $4$ electrons from its $...
0
votes
0answers
280 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 ...
0
votes
1answer
148 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 ...
0
votes
1answer
181 views

Why does this ligand form 6-coordinate complexes with Transition elements and 8-coordinate complexes with Inner transition elements? [closed]

What change takes place in the denticity of this ligand if it is an inner-transition metal ion vs a common transition metal? Primarily, why does the ligand behaves differently with the two situations ...
2
votes
0answers
47 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
725 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
1answer
1k views

Reason for shorter bond between sulphur and oxygen?

I recently came across this sentence in my textbook: the bonds between sulphur and oxygen in oxides of sulphur ($\ce{SO2}$ and $\ce{SO3}$) are much shorter than might be expected for a single bond. ...
3
votes
0answers
63 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 ...