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Why are antibonding molecular orbitals formed?
When two atomic orbitals make one molecular orbital there must be an antibonding orbital also. Why should they make also an antibonding molecular orbital, such as the $2\mathrm b_2$ orbital in the scheme below?
ordinary chemistry student
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17
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What is the difference between distilled water and rainwater?
I am studying different means of collecting water for consumption. From resources available on Internet, I understand that distilled water is not advised for regular consumption because of the lack of minerals and salts, while rainwater can be…
neydroydrec
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Why is pyridine used when making tosyl esters from alcohols?
Tosyl chloride is used to make a hydroxyl group into a better leaving group. However, when the reaction of tosyl chloride and an alcohol occurs, a weak base such as pyridine should be used. Why?
RobChem
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17
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Why would 1kW power supplies fail around Nitric acid (HNO3) gas?
I experienced a situation where some electrical power supplies (rated over 1kW) were exposed to nitric acid ($\mathrm{HNO_3}$) fumes at roughly 9ppm for half a day; these power supplies intermittently failed (perhaps 2 to 3 times per hour) in the…
Mike Pennington
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17
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How does Resonance stabilize a molecule?
How does resonance lower the potential energy of the molecule? Take $\ce{O3}$ as an example.
sedflix
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Why did the salt on the skin of my turkey react with the aluminum foil it was touching?
I sprinkled salt on my turkey skin and left it to dry out over night. It was covered with aluminum foil. The next morning the aluminum foil had holes ‘burnt’ in it and the turkey skin turned silver at the spots where the salt crystals had touched…
Irene
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17
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What do short-range and long-range corrections mean in DFT methods?
Currently I am looking for the most accurate calculation method for a simple non-conjugate molecule consist of C, N, O and H. Normally I would try each method for a similar and known molecule then compare them with the experimental results but I…
gunakkoc
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Is there a simple way to separate deuterium oxide from tap water?
I understand that tap water contains minute amounts of deuterium oxide (heavy water). Is there a simple way to separate, concentrate the $\ce{D2O}$?
docscience
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17
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Why are acetals stable to bases and nucleophiles?
Why are acetals stable to bases and nucleophiles?
Could it be due to electronic effects? Lone pairs on the two oxygen atoms create an unfavorable environment for the approaching nucleophiles and bases. Or could it also be steric factors?
Dissenter
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Number of diastereomer pairs of 1,3-dichloro-1,2,3-triphenylpropane
How can I determine the number of possible pairs of diastereomers here?
My first guess was two: RR with RS and SS with RS. But what about the potential chirality center middle carbon? There are two identical branches attached to it; however, those…
yolo123
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Are carbocations that bad?
My professor has an anti-fetish for carbocations. In any mechanism that we draw with a carbocation, the maximum earnable credit is automatically halved. In any case, he draws all mechanisms involving carbocations as concerted reactions; he never…
Dissenter
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4 answers
Why is a C4 ring impossible?
I am admittedly not a chemist. I was playing with a molecule set recently and I created a ring molecule where I double-bonded four carbon molecules to each other in a ring.
I was in my university's chemistry department, and a passing biochemist…
Jakob Lovern
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What's the purpose of this vintage glassware?
I found this glassware in a phytochemistry lab abandoned in the 1990ies. The piece itself was shelved in the storage room, thus probably already obsolete back then.
The device, entirely glass, is a compact sequence of six bulbs (relative sizes: L,…
I_O
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17
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What is the IUPAC systematic name for methane?
The 1993 IUPAC Blue Book claims that "methane" is a semisystematic name:
Semisystematic names also exist, such as "methane", "propanol", and "benzoic acid", which are so familiar that few chemists realize that they are not fully systematic. They…
Fengyang Wang
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17
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How can I find the symmetry labels of atomic orbitals in a molecule?
What are the symmetry labels for the p and d orbitals of platinum in $\ce{[PtCl4]^2-}$?
I understand how to find the point group of a molecule, but am not sure how to use the character table to find the irreducible representations corresponding to…
Kinformationist
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