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Questions tagged [molecules]

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3
votes
2answers
154 views

Time-dependence in LCAO

I would like to study time-dependence (TD) in linear combinations of atomic orbitals (LCAO). The Hückel method enables quick and dirty determination of MOs for suitable systems (view link for ...
-7
votes
1answer
3k views

Lennard-Jones potential - equilibrium [closed]

If I have Lennard-Jones potential, how can I calculate equilibrium? $$ U(r)=\epsilon \left ( \left (\frac{r_m}{r} \right )^{12}-2 \left (\frac{r_m}{r}\right )^6 \right ) \ $$
3
votes
1answer
980 views

If the temperature of 2 materials are the same does that mean the molecules are vibrating at the same speed?

Pretty much what the title says. My base question is this. Assuming I take a piece of steel, and a piece of PVC plastic and I measure both their temperatures and find they are the same. I then take a ...
11
votes
3answers
606 views

What is the microscopic picture for warm air rising?

The usual explanation for warm fluids rising past cooler ones is that the warmer fluid has a lower density. I'm trying to understand what this looks like at a molecular scale. The density seems to ...
2
votes
2answers
422 views

Why does a coulomb explosion induce fusion?

If you strip the valence electrons apart with a very short intense electromagnetic field the remaining core explodes in a so called coulomb explosion. But experiments have shown that under certain ...
117
votes
5answers
30k views

What does it mean for two objects to “touch”?

If you've ever been annoyingly poked by a geek, you might be familiar with the semi-nerdy obnoxious response of "I'm not actually touching you! The electrons in the atoms of my skin are just ...
1
vote
1answer
23k views

What's the size of carbon dioxide? [closed]

My question is very simple. How big is a carbon dioxide ($\mathrm{CO}_2$) molecule, i.e. the width, length and height of it?
3
votes
1answer
161 views

Experiment to find structure of water

Who first determined the structure of water (two hydrogen atoms stuck to an oxygen atom at approx 105 degrees), and, more importantly, how was this done?
6
votes
5answers
1k views

Why is quantum physics needed to explain photosynthesis?

Why is quantum physics needed to explain photosynthesis? In what aspect does the corresponding classical theories for photosynthesis fail?
4
votes
1answer
12k 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 ...
6
votes
3answers
1k views

Is photon emission possible without electrons changing energy levels?

Does molecular vibrational transition and consequent emission of infrared radiation involve electrons changing energy level? In wikipedia, about vibronic transitions it says "Most processes leading to ...
0
votes
1answer
1k views

Vibrational motion of linear diatomic molecule

This question concerns the following exercise from an old exam: The vibrational motion of a linear diatomic molecule can be approximated as simple harmonic motion. A CO molecule has a bond ...
3
votes
3answers
11k views

Does stirring water in a bucket in whirlpool keeps it warm?

I did an experiment when I was a teenager. I want to prove/see what really went on in that experiment. When taking a bath, take a warm water in bucket and start taking a bath. You will notice that ...
1
vote
2answers
474 views

Subshell notation for hydrogen cation?

Looking at $s$,$p$,$d$ configuration for atoms & ions: Since a hydrogen cation $H^+$ has no electron, how would the subshell notation be written? My best estimate would be $1s^0$.
2
votes
2answers
150 views

What are some molecules stable in outer space that are unstable under terrestrial conditions?

What are some molecules stable in outer space that are unstable under terrestrial conditions? So there are many molecules that violently react on Earth because they're too charged, have unfilled ...
3
votes
2answers
18k views

Sound - what happens with the particles when a wave passes

I'm having some problems in understanding the principles of sound propagation. The wave propagates though air (for example) exerts compression, which is followed by rarefaction. I think I got than ...