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67 views

Why are sulfur trioxide and nitrate not isoelectronic, even though both have the same number of outer electrons?

Though $\ce{SO3}$ has the same number of outer electrons as $\ce{NO3-}$, the two are not isoelectronic. This statement is from JD Lee, but I could not understand why is he calling these two molecules ...
4
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2answers
119 views

Is dihydrogen the only example of overlap between two s orbitals?

I heard that $\ce{H2}$ is the only example of s–s orbital overlap. Can anyone give an example which contradicts this statement?
0
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0answers
106 views

Can 2 dz2 orbitals form a π bond?

Usually , d orbitals overlap sideways along a common internuclear axis, but drawing and checking for dz2 , it always seems to form a sigma bond or null overlap. Is this because it doesn't have any ...
6
votes
1answer
331 views

Valence bond theory and molecular orbital theory — how do they complement one another?

Based on my readings, valence bond theory (VBT) and molecular orbital theory (MOT) tend to complement one another in explaining a molecule, but I don’t understand how VBT helps us explain the ...
-2
votes
1answer
342 views

Why does NH3 hybridize at all?

So in Chemistry class I've been taught that hybridization is a way we can explain things such as how $\ce{CH4}$, for example, forms four, equally strong bonds. However at the same time I'm told that ...
-1
votes
1answer
134 views

Why is a carbon to iodine pi-bond less stable than a carbon to fluorine pi-bond?

This question comes from a second semester undergraduate organic chemistry course. Please refer to the image below with regard to the question. My understanding of the trend in section 4a is that "...
4
votes
1answer
1k views

Ionization energy of C2-, C2, and C2+

My textbook says that $\ce{C_2}^-$ has a lower ionization energy than both $\ce{C_2}$ and $\ce{C_2}^+$. I calculated that the bond orders of $\ce{C_2}^+$, $\ce{C_2}$, and $\ce{C_2}^-$ are 1.5, 2, and ...
3
votes
1answer
721 views

Why do halogens have odd numbers as oxidation number?

Halogens like $\ce{Cl}$ always exhibit $+7,+5,+3,+1,-1$ as their oxidation numbers. I found the following answer after checking several sources: Halogen atoms have $7$ electrons in their valence ...
8
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3answers
1k views

HCH bond angle in cyclopropane and cyclobutane

I understand why the $\ce{CCC}$ bond angles in cyclobutane and cyclopropane are less than ideal $109.5^\circ$ due to the geometric restrictions they encounter in a cyclic structure. However, it is not ...
1
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0answers
162 views

The affect of effective nuclear charge on energy gap between subshells

A few days ago my teacher taught me about $\mathrm{d}$ orbital contraction. He said that in $\ce{SF6}$ the hybridization of sulphur is $\mathrm{sp^3d^2}$. He said that although the $\mathrm{d}$ ...
6
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0answers
386 views

Chemical bonding with f orbitals

For the elements such as rhenium, osmium, iridium how probable is for electrons in the inner 4f orbitals to gain energy and take part in a molecular orbital (such as an $f^2 d^2 s p^3$ hybrid orbital) ...
7
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1answer
721 views

How to explain molecular geometry without the help of VSEPR, valence bond, or hybridization theories?

I was taught, at the high school level, how to rationalise molecular geometries with the help of VSEPR, valence bond, and hybridization theories. However, I have recently also come to know that these ...
3
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1answer
629 views

Hybridisation and the Schrödinger equation

I am slightly confused about hybridisation and how it relates to molecular and atomic orbitals, despite having pored through many sources online. I was hoping someone could verify whether my current ...
8
votes
1answer
524 views

Has it been observed that the dihydrogen molecule dissociates into ions?

As we know from the improved methods valence bond theory (VB), as well as molecular orbital theory (MO-LCAO), the wave function of the $\ce{H2}$ molecule consist of two terms, which belong to covalent ...
1
vote
0answers
144 views

How do we explain shapes of molecules using molecular orbital theory or do we even do that?

How do we explain shapes of molecules using molecular orbital theory or do we even do that ? While reading about the theories to explain chemical combination and stabilities of compounds I read ...
6
votes
1answer
219 views

If I can't draw resonance structures for a pi system, does that mean it doesn't exist?

Whilst trying to answer this question I came across an interesting situation regarding the relationship between resonance structures and molecular orbitals. There are two places that you can ...
0
votes
1answer
150 views

'In MO theory, electrons are treated as spreading throughout the entire molecule'- isn't it exhibited in VB theory also?

First statement: In the molecular orbital theory, the valency electrons are considered to be associated with all the nuclei in the molecule. - Concise Inorganic Chemistry by J.D.Lee. Second ...
7
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2answers
4k views

Hybrid orbitals forming molecular orbitals

My teacher showed me this diagram on how the hybrid orbitals of two atoms combine to form molecular orbitals. I was confused by this because I thought that VB and MO theories were two separate ...
1
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1answer
541 views

Physical Meaning of the Difference between MO and VB Wave Function of H2?

What would be the physical meaning of the difference between the MO wave function and VB wave function of $\ce{H2}$?
7
votes
3answers
6k views

Does the shared electron in Covalent bonds revolve around nucleus?

We know that electrons are charges that revolve around the nucleus. Then, when in covalent bonds the electron is shared; does the electron obey the rule?
20
votes
1answer
209 views

Similarities and Differences between Resonance and MCSCF treatments

Recently, there has been a question by Voldemort concerning different resonance structures of $\ce{NCO-}$, requesting an explanation why one resonance structure would be more preferred than another. ...
8
votes
2answers
1k views

Why is the resonance concept not required in molecular orbital theory?

In valence bond theory, resonance plays a pivoting role; why isn't such concept needed in MO theory? Why is it told that "MO theory provides a global, delocalized perspective on chemical bonding"? (...
32
votes
3answers
19k views

What is actually the difference between valence bond theory and molecular orbital theory?

Recently I have read about both of the concepts in my book (Physical Chemistry by Atkins, Paula). It was literally a reading; though I could understand the language and superposition of orbitals, ...
18
votes
2answers
2k views

What does it mean when it is said that an sp³ orbital has 25% s character?

My textbook frequently mentions: $\mathrm{sp^3}$ hybrid orbital has 25% $\mathrm{s}$-character and 75% $\mathrm{p}$-character. What are these "characters"? And how do these characters influence ...
10
votes
1answer
6k views

Delocalization of pi electrons in nitrate ion

In my textbook, as examples of delocalization of pi electrons, benzene and nitrate ion have been considered. Benzene, due to symmetry of its resonating structures is simple enough. We assume that $\...
2
votes
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 ...
11
votes
2answers
24k 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 ...
6
votes
1answer
171 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 ...
12
votes
3answers
3k 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 ...
3
votes
2answers
2k 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 $...