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1500 questions
37
votes
7 answers
Are metallic/ionic bonds weaker than covalent bonds?
In mineralogy class, I was taught that metallic and ionic bonds are weaker than covalent bonds and that's why quartz and diamond have such a high hardness value. However, in organic chemistry class, I learned that covalent bonds are weaker than…
Tamás
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37
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3 answers
Why do atoms generally become smaller as one moves left to right across a period?
It seems to me that the addition of electrons and protons as you move across a period would cause an atom to become larger. However, I'm told it gets smaller. Why is this?
Tuesday
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36
votes
1 answer
Is there an energy cost associated with flipping the spin of an electron?
THE STORY:
A common example used to illustrate the limitations of restricted Hartree-Fock (RHF) theory is the H$_2$ dissociation energy ($D_e$) curves. RHF enforces electrons to be paired into spin orbitals, $\chi$, or two spatial orbitals $\phi$…
LordStryker
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36
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3 answers
What are the maximum number of electrons in each shell?
In my textbook, it says that the maximum number of electrons that can fit in any given shell is given by 2n². This would mean 2 electrons could fit in the first shell, 8 could fit in the second shell, 18 in the third shell, and 32 in the fourth…
user3034084
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36
votes
4 answers
Why is the letter J omitted in the spdf... sequence?
Under spherical symmetry, the irreducible representations corresponding to $L = 0, 1, 2, \cdots$ are assigned the letters $\mathrm{S}, \mathrm{P}, \mathrm{D}, \mathrm{F}, \cdots$ after which the letters progress in alphabetical order. (The familiar…
orthocresol
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36
votes
4 answers
Does any known substance ignite on cooling?
As the title says, I'm interested in knowing if there is any substance — or combination of substances — that ignites (or even increases its chance of spontaneous ignition) when cooled.
I've never heard of such a thing, nor can I find it in Atkins'…
frodoskywalker
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36
votes
4 answers
Tetrahedral or Square Planar
How can one predict whether a given complex ion will be square planar or tetrahedral when its coordination number is 4 using crystal field theory ?
Is it possible to theoretically predict this?
Sameer
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36
votes
3 answers
A compound that absorbs all visible light
Is there a compound that absorbs all visible light?
oushida
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36
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1 answer
Natural Bond Orbital analysis: Significance of stabilization energy determined by 2nd order perturbation
PREFACE: I am no expert on this topic. My questions at the bottom may be off base. I have some experience with symmetry-adapted perturbation theory (SAPT) when it comes to analyzing intermolecular interactions. The total interaction energy of a…
LordStryker
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35
votes
9 answers
Would it be possible to destroy gold?
I'm a writer. I have a scenario in which a sizable amount of gold needs to be rendered unusable, preferably completely destroyed. I know an acid like aqua regia is able to dissolve gold, but would there be a way to make it impossible (or at least…
Mathias L. Magnussen
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35
votes
2 answers
Chemistry behind Gale's coffee maker in Breaking Bad
Is there a scientific basis for the coffee making equipment which Gale Boetticher describes in Breaking Bad?
He talks about maintaining the right conditions for bringing out the coffee flavor without degrading it.
Ash
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35
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3 answers
Splitting of multiplets in ¹H NMR spectra?
I'm currently taking VCE (Victorian Certificate of Education) Chemistry classes, and we're currently studying the interpretation of spectra produced by Hydrogen NMR (Nuclear Magnetic Resonance) spectroscopy.
When studying the spectra of High…
Anti Earth
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35
votes
6 answers
Why do chemistry and physics have different sign convention in thermodynamics?
In physics class, we write the first law of thermodynamics as $\mathrm dU =\mathrm dQ - \mathrm dW$ and in the physical chemistry class, we write the same law as $\mathrm dU =\mathrm dQ + \mathrm dW$.
The reason being the sign convention is…
user31607
35
votes
3 answers
Why isn't ethane used for cooking?
We commonly use methane and propane for cooking (and home heating), but not ethane. I would expect ethane to be suitable for this, being in between the two, but I've never heard of anyone using it for this purpose. Why is that?
On a related note,…
Joshua Frank
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35
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1 answer
Stereoselectivity of dihydroxylation with osmium tetroxide
Dihydroxylation responds to steric effects and proceeds at less hindered positions. What will be the major product in the following reaction if the reagent used is $\ce{OsO4}$ followed by $\ce{NaHSO3}$?
Won't interactions between $\ce{- OH}$…
Aditya Dev
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