2
votes
4answers
332 views

Two soft questions about spin and the particle nature of electrons

How can we define spin as the spin of an electron around it's own axis if an electron is described by a probability cloud of finding an electron in a point in space? How does that probability cloud ...
2
votes
4answers
209 views

Bond Angles - H2O vs CO2

H2O has a 109.5 degree bond angle, but CO2 has exactly 180 degrees. Is there a qualitative reason for this? It's hard to believe CO2 is exactly 180 degrees unless there were some symmetry, but the ...
3
votes
0answers
79 views

What is a covalent bond?

What is a covalent bond, quantum mechanically? How does it hold the two atoms together, and at one point can you qualify the electron as being shated between two atoms, versus feeling attractive ...
1
vote
0answers
29 views

Covalent Bonds, Varities and Limits!

Related:http://chemistry.stackexchange.com/q/9459/ I was wondering, covalent bonds tend to share two electrons, apparently rarely more than three, and normally between two electrons. Can someone give ...
2
votes
1answer
176 views

Particle in a 1D Box with Symmetric potential: How find solutions?

I am working on a problem in which I shall find the normalised solution to the 1D particle in a box. Solving for the particle in an asymmetric potential is quite straight forward, but I run into ...
4
votes
1answer
373 views

Can we model Chemical Reactions using Quantum Mechanics? If so, what is the most complex reaction we can model?

Not a physicist or Chemist, just interested in QM and it's applications. I've been reading lately about Quantum Chemistry and it occurred to me that since we can model electron orbitals in QM and ...
2
votes
1answer
84 views

Why does bringing N 1-orbital atoms together yield N levels?

A common example of this is that when bringing N hydrogen atoms together into a ring. Far apart, assume each electron exists in the 1s state. As we bring them together, instead of each electron ...
1
vote
2answers
281 views

First principle calculation of boiling point of water

How can we theoretically calculate the boiling point of water at given pressure (other subtle parameters as well, if any)? What is the most accurate (minimum discrepancy with experimental value) ...
1
vote
2answers
120 views

In which direction does the electron move during an electronic transition?

Let's imagine a molecule and put it in a 3D space. Let's also imagine an electronic transition for this molecule. I know how an electronic transition works, how to value if it is possible (using the ...
5
votes
3answers
278 views

Do electrons in multi-electron atoms really have definite angular momenta?

Since the mutual repulsion term between electrons orbiting the same nucleus does not commute with either electron's angular momentum operator (but only with their sum), I'd assume that the electrons ...
7
votes
4answers
4k views

Why do covalent bonds form?

why in a covalent bond are "the bonded electrons are in a lower energy state than if the individual atoms held them at the same proximity"? Also is it correct that " I think when you start pushing ...
1
vote
1answer
160 views

Searching the point group of symmetry

I am engaged in the field of quantum-chemical calculations using programs written by myself. I have found out that I have a problem in finding the point group symmetry of the molecule. The first idea ...
2
votes
1answer
232 views

Electric dipole transitions/expectation value of position

Part of a homework question asks to show that for $\ell=0$ in both $\Psi_i$ and $\Psi_f$, we have $$ \int \Psi_i^\ast \vec{r} \Psi_f \; d\tau = 0 $$ for the position vector $\vec{r}$. (This is for ...
8
votes
3answers
3k views

What makes the difference between ionic and covalent bonds?

Backstory: When I learned about chemical reactions, there were two types of molecular bonds: Ionic, where an atom or compound molecule with a low valence number loses those valence electron(s) to one ...
2
votes
1answer
5k views

Why is oxygen in a triplet state and what are the consequences?

From Wikipedia here and here: ''Almost all molecules encountered in daily life exist in a singlet state, but molecular oxygen is an exception.'' ''The unusual electron configuration prevents ...
4
votes
3answers
643 views

Nanorobots. What stops us from producing them yet?

If we can already predicts accuratelly motion on molecular levels, what stops us from developing small robots to, for instance, navigate through our blood vessels looking for cancerous cells and ...
8
votes
2answers
1k views

Is the Mendeleev table explained in quantum mechanics?

Does anybody know if there exists a mathematical explanation of Mendeleev table in quantum mechanics? In some textbooks (for example in F.A.Berezin, M.A.Shubin. The Schrödinger Equation) the authors ...
8
votes
3answers
743 views

What is the angular momentum spectrum of an sp${}^3$ electron?

So, one thing has been annoying me ever since I learned about orbital hybridization: you explain the shape of molecules by postulating that the orbitals of multi-electron atoms are linear combinations ...
8
votes
2answers
420 views

Explaining valence with quantum mechanics

Can anyone give me a quantum mechanical explanation of the theory of valence? (i.e. why atoms bond just enough to have a complete orbital) EDIT: To clarify, I already have an idea of why atoms bond, ...