Questions tagged [molecules]

An electrically neutral entity consisting of more than one atom (n > 1). Rigorously, a molecule, in which n > 1 must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state. This tag should be applied to question about certain molecules or a class of them.

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The Action of Nitrogen Iodide on Methyl Ketones

I recently encountered two old publications on action of nitrogen iodide on various compounds (Ref.1 and Ref.2). Between them, Ref.1 described the idoform formation by methyl ketones upon treatment of ...
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625 views

How did the first amino acids appear on Earth?

Is there proof or a theory that shows that the first amino acid syntheses on Earth were influenced by a change in heat, gravity, radiation, or something similar?
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3k views

How to explain the periodic trends in boiling points in groups?

Observing the trend of boiling points of the compounds listed, choose the appropriate terms to fit into the blanks: \begin{array}{lr} \hline \text{Compound} & \text{b.p.}/\pu{°C}\\ \hline \ce{H2Te}...
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Measure the complexity of a molecule

Back in April, there was an article in new scientist discussing the work of Lee Cronin, who postulated that molecules of a certain complexity must be biological. Cronin has developed a way to ...
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51 views

Eigenenergies and states of Jahn–Teller molecule

I'm generally interested in numerical chemistry. In our lecture, we have discussed the $E \otimes e$ Jahn–Teller molecule with the following Hamiltonian \begin{align} H = \epsilon n_d + \omega ( a^{\...
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31 views

is there a stead fast rule to predict hybridization or is it just an ad hoc concept

Before I start of this question, Ι want to make it clear that I know that hybridization, like pretty much all of chemical bonding, are just made up to qualitatively rationalize observations. I know ...
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Porous materials: Is the expression of a mean free path $\overline{\ell}$ of the gas molecule valid for a binary mixtures?

Suppose that I have a binary gas mixture at low pressure. Can I calculate the mean free path $\overline{\ell}$ of the gas molecule in a pores of solid material by substituting a molecular weight of a ...
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1k views

Kinetic Diameter: How to calculate it? Pressure influence?

Wikipedia states: Kinetic diameter is a measure applied to atoms and molecules that expresses the likelihood that a molecule in a gas will collide with another molecule. It is an indication of the ...
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370 views

How to rationalise the resonance structures of nitrogen dioxide?

The following image depicts resonance in $\ce{NO2}$ molecule: I don't know if it is obvious or not, but I'm puzzled by this structure. I've read about the structure of the $\ce{NO2}$ compound, but it ...
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103 views

Calculate concentrations in a system made up of molecules in order to calculate ionic strength

I understand how to calculate ionic strength where there are concentration data in molality or molarity units available and where the system is made up of only two components. However, I have been ...
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71 views

Can the friction of air disintegrate objects if they are accelerated enough?

Can an object be thrown so fast that the individual atoms or molecules separate in air? I mean if you could accelerate an object fast enough, would it disintegrate from the friction of air? If so, ...
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94 views

Are the $+\leftrightarrow+$ and $-\leftrightarrow-$ methanol rotational transitions dipole-allowed?

I am quite confused about the origin and justification of the rotational selection rules of methanol, and I would appreciate any help or references. As far as I understand, there are three irreducible ...
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29 views

What is the mean curvature of nitrates and nitrites?

I am reading the book Soft Matter Physics - Synthetic and Biological Self-Assembling Materials from Hamley and particularly page 201. I started to think how this packing occurs in case of molecules ...
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62 views

Amplitudes and phases of transform of an image

I have recorded an image of a large macromolecule and after several types of image analysis, have obtained a rotationally averaged image, that is not quite perfect, but appears to show 6-fold symmetry....
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272 views

First ionization energy of hydrogen molecule

If we have the dissociation's energies of hydrogen molecule $\ce{H_{2}}$($D_{0}$) and the corresponding molecule ion $\ce{H_{2}^{+}}$ ($D_{1}$) together with the first energy of ionization of hydrogen ...
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62 views

Linear equations for constructing molecules with covalent bonds

(By training I am a math-guy and my knowledge of chemistry is restricted to school level) I have read a little bit about the electron spheres and sub-spheres, the Aufbau principle and covalent bonds ...
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60 views

Is there a relation between polarity of molecules and their electric susceptibility?

So it is written in our text that electric susceptibility ($χe$) (the response of say water molecules in the presence of an external electric field) is related to the molecular behaviour of various ...
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136 views

Breaking bonds with magnetic fields

I was wondering if we could break a bond by applying a big magnetic field on a molecule. The magnetic would just cause the spin of cores of the atoms making the molecule to be aligned , raising the ...
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80 views

How would you write the empirical formula of an ion?

How would you write the empirical formula of e.g. X2Y42-?
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109 views

Why does increasing electronegativity difference result in decreasing density?

I've been collecting data and there's a very strong inverse relationship between electronegativity difference and density ($\pu{R^2}$ value of roughly 0.95 from my data). Is there any chemistry that ...
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145 views

Bombarding molecules with electrons

I have been reading a book titled "High Voltage Engineering". It seems to me that in this book it is considered that in a gas when they collide an electron with a molecule, the molecule is stationary ...
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84 views

Are there any reactions where two triatomics form three of the same diatomic?

A chemical equation: $\ce{A}+\ce{B}\to\ce{3C}$ Where $\ce{A}$ & $\ce{B}$ are triatomic molecules and C is a diatomic molecule. Find out $\ce{A}$, $\ce{B}$, $\ce{C}$? So far the most worthy ...
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720 views

Molecular weight of Polymers

Addition polymerisation is defined in my textbook as the process in which a molecule or compound is formed by combination of small molecules (monomers) implicitly having greater molecular mass than ...
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49 views

phase differences between conical intersections and light-induced conical intersections?

I've read recently about light-induced conical intersections, a phenomenon where conical intersections can be artificially introduced to molecules, and that this can be observed even in diatomic ...
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107 views

Can one component of a mixture penetrate the skin if the whole mixture cannot?

There's a general rule that says that compounds under 500 dalton are able to penetrate the skin without any special vehicle (such as ethanol). I've started using castor oil, which contains different ...
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473 views

What radius best represents reaction distance?

Molecules must be within a certain distance for a reaction to begin as well as satisfying a myriad of other factors. Whilst the exact distance varies from reaction to reaction, is their any distance/...
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Diatomic Molecules/Elements

What is the difference between diatomic molecules and elements? Also, If oxygen is element of a single atom, then what makes it a diatomic element? But, then I read that a single oxygen atom can ...
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95 views

Invariants in chemistry used for model selection

What invariants related to geometrical structures that describe molecular geometry are used in chemistry? Explanation: Here, Electronic model with highest prediction rate…, one can learn about ...
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356 views

Polar group strong dipole effect molecular axis

There are some fundamental charactaristics of liquid crystal. One of them is that all liquid crystals are organic compounds and at one side of their long molecular foundation there exists a polar ...
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766 views

Can magnesium chloride absorb water and ammonia at the same time?

Anhydrous magnesium chloride will absorb ammonia to the tune of ($\ce{Mg(NH3)6Cl2}$). Incidentally, magnesium chloride is usually a hexahydrate ($\ce{MgCl2(H2O)6}$) at STP. My question is, could ...
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In molecular symmetry, does capital D stand for dihedral, as lowercase d does? And does capital C stand for center or chiral?

Somehow, I cannot find an answer on the web.... I swear I have looked, but I simply cannot find a direct answer.... P.S.: Some authors use lowercase a, b, and c to refer to certain symmetry operations,...
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90 views

Are all amphoteric substances weak acids and weak bases?

I saw as an example that water is amphoteric (to be more precise amphiprotic), and I came up with the following questions: Is there any substance that acts as a weak acid and a strong bases at the ...
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34 views

Chemical compound scaffolds name

in RDKit, there is this nice function to decompose a chemical compound into its scaffolds. Is there a way to automatically name the scaffolds? I usually search names in PubChem but this may not be ...
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Point group specific definition

Does the term only refer to molecules that have the same symmetry elements or exactly the same symmetry operations. Online I see that its the same symmetry operation however my professor's slides show ...
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33 views

Stability of Peroxynitric Acid in cold temperature

I have a question about the stability of Peroxynitric Acid i.e. $\ce{HO2NO2}$ at cold temperature. I know that it becomes stable when temperature decreases, but what is the specific reason for it? I ...
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32 views

What is the general or ideal equation for the radial wave function?

I came across this question on the internet: What is the value of $(n + l + r)$ in a given wave function, where $n =$ principle quantum number and $l =$ azimuthal quantum number and $r =$ total ...
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How one can calculate Si-O-Ca/Mg valence angle energy?

I want to perform the relaxed scan (or relaxed surface scan) for the valence angle energy of Si–O–Ca, Si–O–Mg, Al–O–Ca, and Al–O–Mg. I will use DFT (ORCA), probably B3LYP and triple zeta basis set (...
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Molecular weight of NiMnGaFe compund problem

I have a big problems calculating molar/molecular etc masses, because in my case I have a monocrystal, co I cannot imagine it as a molecule and my compound is made of Ni-Mn-Ga-Fe. I know the mass and ...
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What are molecular species?

I am in high school learning about adsorption for the first time. My school textbook says: "The accumulation of molecular species at the surface rather than in the bulk of a solid or liquid is ...
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If cigarette smoke is exhaled, what happens to the accompanying exhaled breath?

I want to know what happens to that breath. To help you answer this question, consider in your mind these subquestions: Is there a necessary principle at work, by which you know that it vanishes/...
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Can somebody help me understand this sentence?

"The molar enthalpy of vaporisation of a liquid is the enthalpy change when one mole of the liquid changes into one mole of its gas at the boiling temperature." The part which i am not sure of is the ...