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.

Filter by
Sorted by
Tagged with
11
votes
1answer
131 views

Oxide content description

From time to time, I come by to see what people do with my mhchem package. Here, I came across a notation that I did not know yet: $\ce{K2O-nSiO2-xH2O}$ and $\ce{K2O - 3.2SiO2 - 2.7H2O}$ What is this?...
6
votes
2answers
1k views

Three stacked arrows, what does it signify?

I was checking the mechanism for the Lossen Rearrangement, when I came across the chemical reaction denoted as follows: I couldn't find any resource where this notation was talked about. What do the ...
2
votes
1answer
66 views

What does A. R. in A. R. sodium nitrite mean?

I'm reading about a reaction from a 1970s organic chemistry book. It references A. R. sodium nitrite. What does the A. R. mean? I see from online that "Ar" means aromatic ring. Is that the ...
0
votes
0answers
36 views

Writing water as a reactant in acid/base dissociation (Brønsted Lowry)?

The dissociation of $\ce{HCl}$ in water is written as: $$\ce{HCl (aq) -> H+ (aq) + Cl- (aq)} \tag{1}$$ Sometimes we also include $\ce{H2O}$ as a reactant to stress the fact that the protons are not ...
3
votes
2answers
829 views

What is LSD-1, …, LSD-24, LSD-26, …?

LSD (lysergic acid diethylamide) was formerly often referred to as ‘LSD-25’. If it really is a (Albert Hofmann / Sandoz)'s code name (and not a combination of ‘LSD’ and usual LSD (Delysid) dosage ...
2
votes
1answer
3k views

What is the difference between λ and Λ with regard to molar conductivity?

I came across these equations (boxed in red) in a book: $$ \begin{align} &\therefore & t_\mathrm{c} &= \frac{u_\mathrm{c}}{u_\mathrm{c} + u_\mathrm{a}}\\ &\text{and} & t_\mathrm{...
0
votes
2answers
65 views

Rules to follow while writing a chemical formula for polyatomic ions

In Science, textbook for class IX, chapter $3$ [1,p.38], it states: The rules that you have to follow while writing a chemical formula are as follows: in compounds formed with polyatomic ions, the ...
23
votes
3answers
73k views

What is the meaning of the “dot” notation in chemical formulas?

For example for 4 given elements A,B,C,D, what's the meaning of $\text{AB} \cdot x \text{CD}$?
8
votes
2answers
927 views

Superscript and subscript together after the same atom

In the chemical formula of some ion compounds, there is the necessity to write the charge in the superscript and the numbers of atoms in the subscript, but together at the right of the same symbol ...
3
votes
3answers
3k views

Drawing the condensed structure of ethylcyclobutane

The IUPAC name for this is ethylcyclobutane. I know that the formula is $\ce{C6H12}$. I have no problems drawing the skeletal structure, but I have a little difficulty drawing the condensed structure....
6
votes
2answers
638 views

What does K° signify in this reaction?

What does the K° signify in the above reaction. Is it just a typo, or is it supposed to symbolize something? EDIT: This screenshot is from the solutions manual. In the original textbook, the author ...
9
votes
1answer
5k views

What are SN1' and SN2' reactions?

I went through the problems on the pictures: The answer of the problem 119 is $\mathrm{S_N1'}$, and that of 120 is $\mathrm{S_N2'}$. I actually can't figure out what $\mathrm{S_N1'}$ ($\mathrm{S_N1}$...
12
votes
1answer
563 views

Typesetting of the retardation factor (Rf)

What should be the typesetting for the symbol of the retardation factor as used in thin-layer chromatography? These are the possibilities: Rf - only f in italics Rf - both R and f in italics Rf - ...
2
votes
1answer
116 views

Convention in electrochemical cell notation

While writing the cell notation for a cell, doesn't one have to write the two states in which a species exists in a sequence appropriate to the reaction in which they participate? For example, in the ...
0
votes
1answer
66 views

Proper notation of doubly charged ions

I have always notated doubly charged ions with a superscript $++,$ such as $\ce{He^{++}}.$ For more highly-charged ions I would denote them with the number of charges, such as $\ce{Pt^{4+}}.$ ...
2
votes
2answers
468 views

pH notation in text

When referring to units of pH in continuous text (i.e. not in a table), which is the recommended usage? pH 7 to pH 8 pH 7 to 8 What about when the term "pH" has already been mentioned in the text? ...
3
votes
2answers
1k views

What do the brackets mean in this inline structure representation?

Based on the way the molecular formula is written — $\ce{Br(CH2)4Br}$ — I'm assuming this means that there are $4\ \ce{-CH2}$ groups attached to $\ce{Br}$. Am I correct? I've always thought that $\ce{...
17
votes
2answers
1k views

What is the “‡” symbol meaning in a reaction mechanism?

I was studying hydroboration from Clayden's Organic Chemistry [1, p. 1281] and the transition state had “‡” symbol in the upper right corner of the activated complex: We know that this is not the ...
0
votes
2answers
89 views

How to identify if a material is perovskite or not?

This is more of a materials science question, but I believe many of you have referred NIST Inorganic Crystal Structure Database (ICSD) database. I am collecting a database of perovskite materials and ...
8
votes
1answer
750 views

What is the @ symbol used for in material science?

I came across the phrase "Silicone Rubber/Paraffin@Silicon Dioxide" also written as $\ce{SR/pa@SiO2}$, utilising the @ symbol. How can I understand what this means?...
19
votes
1answer
69k views

What are t2g and eg in CFT?

In the crystal field theory (CFT), when the splitting of the d-orbital occurs, it gets divided into two parts. The upper part with higher energy is the $\mathrm{t_{2g}}$ and the lower part with lower ...
3
votes
2answers
1k views

How should a triple bond be depicted in skeletal structures?

Draw the skeletal structure for the following compound: $$\ce{HOCH2CH2OCH2C#CCH2CH(CH3)2}$$ I can't figure this out. I can draw it up until the triple bond. My professor marked off because the ...
7
votes
2answers
1k views

What databases or repositories are there that have generalized SMILES for functional groups?

Does a resource exist that has the SMILES formula of the generalized pattern that represents the group? For instance: I have the aldehydes group, which has the pattern: ...
0
votes
0answers
44 views

What is the correct electron dot notation of carbon?

My book says that the dot notation for Lewis structure of carbon has 2 possible ways: two dots on the right, one on the top, one on the left one dot on all four sides Why are both of these correct? ...
5
votes
1answer
56 views

Notation in atomic structure

In the book, The theory of atomic structure and spectra, Robert D. Cowan says that the allowed terms of $p^2$ are $^1S$, $^1D$, $^3P$ and so the possible terms of $p^2 + p\quad$ (obtained by using the ...
1
vote
1answer
26 views

Writing a organic reaction in different form

Can I write this reaction $$\ce{A + B ->[\ce{X}] C + D ->[\ce{Y}] E + F}$$ as $$\ce{A + B ->[\ce{(1) X}][\ce{(2) Y}] E + F}$$ Can I write any organic reaction in this way or are there any ...
-1
votes
1answer
76 views

How do I denote a measurement with a margin of error using ±?

I am trying to express a quantity that is measured to be $\pu{0.75 mL}$, but could be anywhere between $\pu{0.7 mL}$ and $\pu{0.8 mL}$. Is this the correct way to do it? $$\pu{0.75 mL} \pm \pu{0.05 ...
2
votes
1answer
37 views

Connection between irreducible representations and electronic states in diatomic molecules

I am trying to understand the connection between irreducible representations and molecular electronic states. To explain the problem: I found some potential energy curves (PECs) for $\ce{N2+}$ in the ...
13
votes
2answers
7k views

Correctness of writing H3C as opposed to CH3 in a carbon chain

I have been studying alkanes, alkenes & alkynes for a while, and I see in the examples that all the basic structural formulas start with $\ce{CH3}$, then $\ce{CH2}$, and the last carbon atom is $\...
0
votes
1answer
38 views

Question on notation

Here, when they write $v/(\mathrm{mol\ s^{-1}\ (kg\ \text{protein})^{-1}})$ is $0.30$ for the first row first column, do they mean that the value is $0.30\ \mathrm{mol\ s^{-1}\ (kg\ \text{protein})^{-...
2
votes
1answer
262 views

Why do we write electrode potentials next to chemical reactions? [closed]

We might have a half cell consisting of the redox couple $\ce{Ag+}/\ce{Ag}$, which for example's sake might be fixed to be at the cathode (i.e. undergoing reduction). The reaction at the cathode is ...
3
votes
1answer
1k views

What does (sol) in a chemical equation mean?

I'm reading Shrivers Inorganic Chemistry book and some of the equations have a (sol) state on them. I'm sure the book has already defined this but I cannot find where. Examples: \begin{align} \ce{[...
1
vote
1answer
39 views

Formating a chemical equation - Physical states

I study chemistry in an University and I have two professors that says opposing things. One says that the physical state must be subscribed (1 at the picture) and other that it must be written to the ...
5
votes
1answer
7k views

What is difference between T1g and T2g?

I know that the “$\mathrm{g}$” stands for symmetry of octahedral shape, but how are labels “1” and “2” given in $\mathrm{A_{1g}}$ and $\mathrm{A_{2g}}$ representations too… Is it related to group ...
2
votes
1answer
534 views

Molar heat capacity and heat capacity

Is molar heat capacity and heat capacity at constant volume both represented by $C_v$? at constant pressure both represented by $C_p$?
6
votes
1answer
107 views

How to calculate molar mass of (6)UO2+2D and (6)UO2OH+D?

For a hydrogeochemistry project, I want to calculate the molar masses of some compounds. I came across a problem when encountering species like (6)UO2+2D (aq) and <...
4
votes
1answer
76 views

Has anyone encountered the use of Omega to represent equilibrium?

One of my lecturers last year (a pharmacologist by training) used the symbol $\Omega ^m$ as a shorthand for equilibrium. He implied it was common practice but I've never come across it elsewhere. I ...
3
votes
0answers
57 views

Is there a standardized way to assign a label to the symbol of a chemical element (in a published work)?

When referring to a particular atom, both in text and when using a graphical representation, several conventions are being applied. In the field of crystallography an arabic numeral either follows ...
0
votes
1answer
105 views

How to distinguish mass concentration and density?

I am writing a proof where I have to mention both with density and of a material and mass concentration (mass/volume) of a material. I am using the letter $\rho$ to represent density, and I didn't ...
3
votes
1answer
45 views

An exception to the IUPAC convention for italicisation (typography)

According to IUPAC, only physical quantities and variables must be italicised. Section 8 Use of Italic and Roman Fonts for Symbols in Scientific Text of ICTNS Guidelines for Drafting IUPAC Technical ...
16
votes
3answers
8k views

Which one is the best notation for sodium acetate

I have seen two different notations for sodium acetate. The first one is: $$\text{NaCH}_3\text{COO}$$ The second one is: $$\text{CH}_3\text{COONa}$$ Now I'm confused, which one is the best to use?
11
votes
2answers
728 views

Proper common notation for a ligand

I've observed several notations for the ligand in the literature in general, say, for the typical complexes like $\ce{MX_n}$ ($\ce{M}$ - metal) where ligand $\ce{X}$ is denoted as (according to my ...
-1
votes
1answer
293 views

Confused on how to draw cis-[Ni(H2O)4(NH3)2]Cl2 [closed]

I got a question on my practice exam telling me to draw cis-diamminetetraaquanickel(II) chloride, but I'm not sure on how to place the two $\ce{Cl}$ atoms.
0
votes
1answer
94 views

Meaning of mass concentration “units” % m/v [closed]

In a saline solution that is 5.750% (m/v) potassium iodide $(\ce{KI}),$ there are: a) 5.750 mL $\ce{KI}$ per 100.0 mL $\ce{H2O}$ b) 575.0 mg $\ce{KI}$ per 10.00 mL of $\ce{KI}$ solution c) 5.750 g $\...
7
votes
2answers
24k views

Why is ethanol written as C2H5OH not C2H6O?

This is balanced equation of fermentation of glucose: $$\ce{C6H12O6(aq) -> 2C2H5OH(aq) + 2CO2(g)}$$ I know that the result of glucose fermentation is ethanol ($\ce{C2H6O}$). What represented in ...
0
votes
2answers
67 views

Why do we use [H⁺] and [OH⁻] in balancing redox reactions instead of using [H₃O⁺] and [OH⁻]? [duplicate]

For what reason is it universally agreed upon that we use $$\ce{H+ + OH-}$$ ions in balancing water on either side of the reaction, but not the $$\ce{H3O+}$$ ions?
12
votes
2answers
658 views

“T” in subscript in formulas

Does a “T” in a formula subscript indicate all possible numbers of atoms? $\ce{FeO_T}$ is the specific one I came across (in the "bulk chemistry" table here: https://sciences.ucf.edu/class/...
10
votes
3answers
1k views

What does a comma signify in inorganic chemistry?

$\ce{(Ca{,}Co)CO3}$ I have never ever seen this before. What does this mean exactly?
4
votes
1answer
85 views

Phase description for a substance dissolved in a solvent other than water?

I'm trying to write an equation for which I have $\ce{CuI}$ dissolved in acetonitrile. Usually if you have a salt dissolved in water you can denote that using $\ce{(aq)}$, but is there a notation for ...
10
votes
1answer
6k views

What are the correct equilibrium arrows?

I was recently subject to some atrocious teaching. One of the gems that found me was the equilibrium arrow usage. I am accustomed to write $\ce{<=>}$. Yet, the entire class had to use ⇆ ...

1
2 3 4 5