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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85 views

Kinetic Theory of Gases and molecular velocities of gases [closed]

The assumption that molecules collide with elasticity was postulated in the kinetic theory of gases. So my question is molecules should have higher tendency to collide obliquely and would therefore ...
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Why are moles of compounds have only 6.022x10 23 atoms? [closed]

I am a bit stuck on a basic chemistry concept. I understand that the Avogadro number indicates the number of chemical entities it has (ion, molecule or atom) What I don't understand is that when you ...
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What makes a compound a dehydrating agent?

When a carboxylic acid with low molecular weight is heated with $\ce{P2O5}$ we get the corresponding anhydride. My book says that this reaction happens with dehydrating agents such as $\ce{P2O5}$. I ...
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Can you calculate the properties of a substance based solely on its atomic properties?

I'm trying to write some software that I can use to determine, roughly, what the physical properties of a pure substance are. I know I could just use a database of the known properties of each element,...
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Identifying molecule with three adjacent six-membered rings from blurry image

I have found this isolated image on one of my old hard drives and I would like to know what molecule does the image represent:
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1answer
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How to determine the empirical formula given mass percentages of the elements and the molecular weight?

A compound has $67.3 \% \rm~C,4.62 \%~N,6.93 \%~ H$ and O. Determine the molecular formula of the compound knowing its molar mass is $283\rm~\frac{g}{mol}$. My solution : The percentage for the ...
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1answer
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What is the use of both mol and mass representing the same thing i.e. amount of something? [closed]

A mol is a unit but also has a magnitude. How can a unit have a magnitude? And if mole is used to measure an amount of substance than what does mass measure?
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How different are molecule with same connectivity

Let us represent molecules by graphs (atoms are vertices and bonds are edges). Let $A$ be the adjacency matrix of the molecular graph. $A_{ij} = b$ where $b$ is either binary: 0 when atom i and j are ...
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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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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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Is there a way to use free software to convert SMILES strings to structures?

So far I've been unsuccessful in finding an open source tool that will convert a large number (>100k) of SMILES strings to a chemical structure. Is this really only solved by commercial applications? ...
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Database for experimental diatomic ionization energies

I am looking for a database, in which the experimental ionization energies (and e.g. heat of formation) of atoms and diatomic molecules are listed as files. If it comes with a Python package, that ...
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1answer
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Can atomicity be infinity? [closed]

My chemistry teacher told us that graphite or diamond had an atomicity of infinity. However, the definition of molecule in my testbook is A molecule is the smallest part of an element or compound ...
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Why do the atoms in molecular models have the colors they have?

Molecular models are a great tool for visualizing a molecule in three-dimensional space. These models even appear on the web (practically every chemical's Wikipedia page), and there is a very specific ...
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Law of Multiple Proportions: What is the significance of small whole numbers?

I'm new to Chemistry and in my textbook, it describes the Law of Definite Proportions (aka Proust's Law) and then goes on to describe the Law of Multiple Proportions. The example they give is carbon ...
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Software that determines whether a molecule can exist and draw it from a formula?

I have run calculations that predict atomic configurations. As a simple example, in a system that contains H and O, I might get a list like: ...
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Molecular formula with CH without numbers [closed]

I was wondering if there exists a compound, the molecular formula for which includes CH but does not include any numbers. Like ...
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What do we learn from an isotope peak (or M+2 peak) in a mass spectrum?

Mass spectrum of a molecule showed molecular ion peak and its isotopic peak in 1:1 ratio. What is the possibility of the atom present in the molecule? Since it is mentioned that it has a ...
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Why does SO2 have a larger bond angle than H2O, H2S, and NH3

So we have to find which of the follwing compounds has the smallest bond angle: $\ce{H2O}$, $\ce{H2S}$, $\ce{NH3}$, $\ce{SO2}$. So L $\propto \frac{1}{BA}$ where $L$ is the number of lone pairs and $...
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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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1answer
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What is kekulization (in RDKit)?

It's been a while since I've studied chemistry. Now, I am reading the documentation of RDKit. At a certain point, the term "kekulization" is mentioned. What is kekulization (in RDKit, if this is not a ...
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Is water the most common multielemental compound?

Water is a very common substance, not just on Earth, but also in space. Although water usually occurs in space as a solid and occasionally as a gas and relatively rarely as a liquid, the most common ...
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1answer
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What is a molecule’s smallest set of smallest rings?

It is been a while since I've studied chemistry. Now, I am reading the documentation of RDKit, where they mention the expression "smallest set of smallest rings" (SSSRs). I understand that a ring is a ...
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Do symmetric hydrogen bonds in neutral molecules exist?

As far as I know, there have only few truly symmetric hydrogen bonds been observed. Unquestionable is the existence of it in the bifluoride ion, $\ce{[F-H-F]-}$, see also here. There are a couple of ...
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When we tear a piece of paper do some of the molecules fall of as we tear? [duplicate]

So I mean are some of the molecules lost(fall of) while we tear the paper? Or all the molecules present in the sheet of paper just get divided in the two new pieces created?
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What is molecular potency?

In the paper Junction Tree Variational Autoencoder for Molecular Graph Generation, the authors propose a ML model that is based on the message passing neural network, variational auto-encoder, the ...
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Are long oxygen molecules possible?

Are large oxygen containing molecules possible? Either large rings, or chains with hydrogen atoms at the ends. Like this: $\ce{H-O-O-O-O-O-O-O-O-O-$\cdots$-O-O-O-O-O-H}$
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1answer
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Is the proper formula for phosphorus oxide(V) P4O10 or P2O5?

I would like to ask about formula of phosphorus oxide(V). Should it be $\ce{P4O10}$ or $\ce{P2O5}$? Which is right when I have to write the molecular formula?
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1answer
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Collision rates between two molecules in a liquid

How would I calculate the collision rate between kaolinite and amylopectin particles in a liquid with a density of ($\pu{1.01g/m^3}$) and a viscosity of ($\pu{0.000434 Pa s}$)? I know this is related ...
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Is the molar mass of a molecules lowered by the binding energy of the chemical bonds?

When calculating the molar mass, is there any measurable difference in total mass of the molecule due to the loss of binding energy?
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How to represent a 3D model of cocaine?

For my AP Chemistry class we were told to make a molecular diagram that was "better than excellent" and the rest is up to us (we could choose the molecule and how we wanted to represent it). My group ...
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Is a diamond a single molecule?

Assuming a perfect diamond with no impurities. Would this diamond considered to be a single large molecule? Browsing the interweb I found several opinions about this but did not find a clear Yes or No....
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Choose the molecule with the strongest bond

Choose the molecule with the strongest bond: $\ce{F2, Cl2, Br2, I2,}$ or all are equal. All of them are nonpolar-covalently bonded, so I had thought that the answer would be "all are equal". However,...
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Predict the number and nature of bonds using Molecular Orbital Theory

I found the following question in a high school chemistry problem book: According to Molecular Orbital Theory which of the following is true: (A) In $C_2$ molecule both the bonds are $\pi$ ...
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How to determine the boiling point of substances? [closed]

Which of the substances has the lowest boiling point? a) $\ce{H2O}$ b) $\ce{H2S}$ c) $\ce{H2Se}$ d) $\ce{H2Te}$ I've been searching for any formula or rule to determine this, but I read that it ...
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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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1answer
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Why can you blow bubbles in milk but not hot cocoa, which is milk based?

My daughter is asking this question and I’m assuming it’s something related to the cocoa added to milk but don’t know what change is happening molecularly and why it would affect the bubbles. Thanks! ...
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Is the existence of chirality center equivalent to chiral?

To make my question more clear, I want to ask two questions: Is it possible for molecule to be achiral even though molecule has chirality center? Is it possible for molecule to be chiral even ...
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What is the structure of N₅P₃?

What is the structure of the molecule $\ce{N5P3}$? $\ce{N5P3}$ is not documented online, so could anyone please comment on the structure of the molecule: How many ligands does each phosphorous atom ...
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Existence of Dichlorine Pentoxide

I searched the net and a lot of books, but I was unable to find any information about dichlorine pentoxide. Does dichlorine pentoxide($\ce{Cl2O5}$) exist? If it doesn't exist, then why so? If ...
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What is the difference between physical and chemical bonds?

If you characterize the chemical bonds to two categories physical and chemical bonds, how do you do it? Aren't all bonds chemical and physical? From the freedictionary.com, chemical bond: Any of ...
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How to quantify the difference between two xyz files for the same molecule?

Sometimes I encounter xyz files with slightly different coordinates, for example, before and after optimization. What is the easiest way to compare how different are they? In the first approximation,...
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1answer
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Lennard-Jones diagram - what is on the x-axis?

I have a Lennard-Jones diagram here where I can't figure out, what is on the x-axis. G. Ertl, Angew. Chem. Int. Ed. 2008, 47 We are looking at a diagram for a molecule $\mathrm A_2$ composed of two $...
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Methylcyclohexane chair conformers

I am trying to create the molecule of the methylcyclohexane in the equatorial and axial conformers. I read in this site about the chair conformation. My molecule looks like the following picture (...
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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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Long linear molecule with alternating elements? [closed]

In the classic freshman physics text Electricity and Magnetism by Purcell, one of his first examples is the computation of the electrical binding energy of a $\ce{NaCl}$ crystal. He models the crystal ...
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Why is NO2 formed when N valency is 3

Sorry if the question is silly but this is troubling me more than enough. Here's what I know about chemical formula: Reverse the valencies of the combining elements. But in this case, $\ce{NO2}$ is ...
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Which has the greater N–O bond length, NO₂⁻ or NO₃⁻?

Which has the greater N–O bond length, $\ce{NO_2^{-}}$ or $\ce{NO^_3^{-}}$? I don't understand why the N-O bonds should be of different lengths in these two molecules (don't the same bonds have the ...
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Do molecules containing only carbon exist?

Why doesnt carbon forms bonds with itself to form a molecule. Carbon shows the property of catenation then why doesnt it form a cyclic molecule as : ...
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How many isotopologues of water are there?

If ordinary water molecules can contain any of the three hydrogen isotopes, $\ce{^1H}$, $\ce{^2H}$, $\ce{^3H}$, and any of the three oxygen isotopes, $\ce{^{16}O}$, $\ce{^{17}O}$, $\ce{^{18}O}$, how ...