Questions tagged [notation]
A system of written symbols used to represent qualities or quantities, elements or molecules, or formulas in general. Usually a notation follows a convention or a guideline, often published by IUPAC-IUPAP. This tag should be used for questions regarding the proper use of a notation or misleading or uncommon notation in the scientific literature. Do not confuse this tag with the [nomenclature] or [terminology] tags.
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What do bracketed plus-sign-notations such as (+M) or (+O2) next to reaction participants mean?
What does $(+M)$ means in the following reaction from Chua et al. [1]?
$$\ce{NO2 + OH($+M$) -> HNO3($+M$)} \tag{R11}$$
It looks like $M$ could be a catalyst (maybe metal?), but usually catalysts ...
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What does ‘S/A’ mean in SMARTS pattern when using Chemicalize to draw the chemical structure?
I am still new to the SMARTS annotation. I am wondering what does S/A’ mean on the bond labeling drawn with Chemicalize using SMARTS [!#1]c1n[cH]nc([!#1])c1[!#1]? ...
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What does ‘(A)’ mean in SMARTS pattern when using Chemicalize to draw the chemical structure?
I am not quite sure what ‘(A)’ could mean for the carbon atom when writing the SMARTS CCN(C)C using Chemicalize to draw the chemical structure below. Can anyone ...
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Meaning of letter K in chemistry conventions [duplicate]
The letter "K" is usually used as chemistry (or statistics/ physics) conventions, take the equilibrium constant (Kc) and rate constant (k) as two prime examples.
Are there any reasons why &...
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Is there a symbol or representation for tolyl groups as there is for the phenyl group?
Is there a symbol or representation for tolyl groups as there is for the phenyl group?
Phenyl group is often represented by "Ph" when for a matter of space you can not draw the entire ...
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Why can you "cancel out" chemical species from a chemical equation that appear on both sides of a chemical equation?
Why is it acceptable in chemistry to "cancel out" chemical species from a chemical equation that appear on both sides of a chemical equation (as reactants and as products)?
On the one hand, ...
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How do I denote a specific rovibrational transition?
I am using a linelist from HITRAN, which gives me a whole lot of extra data and I want to denote the transitions accurately. But I don't know what to use for rovibrational transitions. The following ...
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How to obtain the expression for residual Gibbs energy?
The property involved is Gibbs free energy, the equations that I wrote are presented in my text book Introduction to chemical engineering thermodynamics by Smith and Van Ness, Chapter 6.
The thing is ...
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Parentheses use in non stoichiometric compounds
When should one use (or not) parentheses in writing the formula for non stoichiometric compounds.
I mean, the mineral sphalerite is often represented by the formula $\ce{(Zn,Fe)S}$ and, all though I ...
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What is the meaning of "*" in this compound notation?
I am reading a book on hydrogen energy (handbook of hydrogen energy), and came across the following compound on the Cu-Cl thermochemical cycle: $$\ce{CuO\text{*}CuCl_2(s)}$$
What exactly is the role ...
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How to make bonds thicker in ChemDraw?
I often see molecules depicted using ChemDraw with all or selected bonds visibly thicker than those used with the style defined with ACS-1996 template.
For example, see the PDF handouts for Baran's ...
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What do consecutive letters A and B in the 4th column of PDB file signify?
What do the consecutive A and B in the 4th column identify in a PDB file downloaded from rcsb.org?
The molecule name is 3CZ3 (...
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Notation for spectral density in experimental community
In an open quantum system setup where the system is coupled to infinite harmonic oscillators as bath (as in the Caldeira leggett model, for example), through the Hamiltonian,
$$H = \frac{\hat{p}^2}{2m}...
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Line Entry system like SMILES for metals?
SMILES is not designed for metallic compounds.
Is there a similar ASCII line entry notation for metallic compounds, including repeating structure in space, &c.?
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What is the point of the up arrow (↑) which shows "gas evolved" or "gas liberated", if you could just write the state symbol (g)? [closed]
What is the point of the up arrow (↑) which shows "gas evolved" or "gas liberated", if you could just write the state symbol (g)? And would you write the up arrows (↑) and down ...
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Total vs. Partial derivatives in kinetics
I've recently seen partial derivatives in the velocity definition but in most cases is with total derivatives (infinitesimal change of concentration over infinitesimal change of time).
Maybe is more ...
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Convention for writing concentration units
1st part of my question:
Q) The concentration of an NaCl solution is 1M. Express this in percent wt. by vol. unit.
Ans:
$$\text{In %(w/v) unit}=\frac{58.5\pu g}{1000\pu{mL}}\times \frac{100}{100}=5.85\...
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What does $n$ represent in "hydrated compound⋅nH2O"? [closed]
On Wikipedia it is written that in "hydrated compound⋅nH2O" $n$ is the number of water molecules per formula unit of the salt. I don't understand what that means and this is indicated in ...
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Notational inquiry regarding nuclear chemistry
I'm aware that the notation for an element (with a charge) is as follows:
$$\large ^{~~~\text{mass number}}_{\text{atomic number}}(\text{element symbol})^{\text{charge}}$$
However, during beta decay (...
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Chemical formulas with non-integer coefficients [duplicate]
Let's consider the composition $\ce{Hg_{0.7}Cd_{0.3}Te}$ which appears in my data.
As I remember from my chemical knowledge it's not possible having non-integers numbers as coefficients of elements. ...
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How are names for atomic orbitals with high $l$ generated?
I'm looking at Table of Real Spherical Harmonics and trying to understand how the names for the real orbitals are generated. Note that I'm a physicist. In chemistry parlance, I'm trying to come up ...
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Caffeine molecule representation and orientation
Almost all the representations of the caffeine molecule that I've come across have the two rings drawn next to each other on the horizontal axis.
Any particular reason for this?
Would it be sacrilege ...
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Is there a canonical variable for period and group?
For example, "Z" is the standard symbol for atomic number. I'm writing a manuscript that uses the group and period of elements within some equations, and so far I'm just denoting them as $G_{...
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Are there examples of molecular formulas with nested groups?
Sometimes a molecular formula is written using groups, for instance $\ce{Al2(SO4)3}$.
Are there examples of formulas with nested groups, such as $\ce{ABC[MNO2(XYZ)4]3}$ or is this avoided?
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Unique notation to search for compounds in PubChem and in Chembl
I am not a chemist, I come from a computer science background. I am working on a project related to computer-aided drug design.
I have a list of chemical compounds in their SMILES notation, to which I ...
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How many characters does the SMILES notation uses? [closed]
I am not a chemist, in fact, I come from a computer science background, however, I am working on a project that involves using machine learning for SMILES generation.
My question is, how many ...
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Symbol to denote a group which is either an oxygen atom or NH group
I'm drawing the generic structure of several different organic molecules in my thesis. They share some features, one of which is a carbonyl carbon attached to either an oxygen atom (i.e. ester) or an $...
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Meaning of $^2[\,1/2]$ terms in atomic spectroscopy
I was trying to analyze some atomic emission spectroscopy data and I encountered unfamiliar notation of the terms for me.
Commonly, the electronic states of the atoms can be described by quantum ...
user76255
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Is Avogadro's constant equal to 1? [closed]
The mole is defined to be exactly $\mathrm{mol}=6.02214076\cdot 10^{23}$ entities. Avogadro's constant is defined as $N_A=6.02214076\cdot 10^{23}\mathrm{mol}^{-1}$.
Then why is it not usual to write
$$...
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Is a change in delta-delta-G typically notated as delta-delta-delta-G?
I'm currently writing a research paper, and need to refer to a difference between $\Delta{\Delta}G$s. The naive way to notate this would be $\Delta{\Delta}{\Delta}G$, but that looks cumbersome and ...
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