Chemistry Stack Exchange
Chemistry Stack Exchange

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.

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 or recommended by IUPAC-IUPAP.

Information on specifically chemical notation can be found in the electronic library of the IUPAC.

Related:

263 questions
27
votes
2 answers

What does this lambda–sigma notation mean?

I am currently reading the CRC Handbook of Phosphorus-31 Nuclear Magnetic Resonance Data by John C. Tebby (CRC Press, 1991) and on several figures (ex. pages 9 to 14) there is a caption that reads along these lines $\ce{^{31}P}$ NMR chemical shifts…
Canageek
  • 1,741
  • 2
  • 15
  • 27
27
votes
3 answers

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 $\text{AB} \cdot x \text{CD}$?
Sparkler
  • 4,257
  • 5
  • 38
  • 61
24
votes
3 answers

Why is the minus sign (-) not allowed in reaction equations?

Recently in my chemistry class, the teacher told us that while writing "half equations" (such as a sodium atom losing one electron to form a sodium ion) we were not to use a simple minus sign. We were only allowed to use a plus sign. For example,…
James Smith
  • 341
  • 2
  • 5
20
votes
3 answers

Superscript open circle notation in formula

I may be only a physicist but I'm familiar with the superscripted dot to indicate a radical. In a paper I'm reading the authors have also used a superscripted open circle. I can't find any reference online or in my physical chemistry textbook…
Chris H
  • 366
  • 1
  • 12
18
votes
2 answers

Arrows used in chemical reactions

A point was raised about arrows used in a chemical reaction. I think we can all agree that $\ce{->}$ arrow in the reaction $$\ce{A + B -> C} \tag{1}$$ means that the reaction goes in one direction. But what of $$\ce{A + B <-> C} \tag{2}$$ $$\ce{A +…
MaxW
  • 22,242
  • 2
  • 36
  • 80
18
votes
2 answers

What does a number in brackets after another number mean? I.e. 21(1)cm-1

What does the number in brackets mean in these two examples? $$21(1)\ \mathrm{cm^{-1}}$$ and $$1.0(3)\times10^{-7}$$
draksi
  • 491
  • 2
  • 5
  • 13
16
votes
1 answer

Typography of Orbitals

For mhchem, I need to decide on a typographical representation of orbitals. Wikipedia tells me, there are atomic orbitals with letters s, p, d, f and g. In a later table, there is even h. Then, there are molecular orbitals with greek…
mhchem
  • 3,316
  • 2
  • 16
  • 34
16
votes
3 answers

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?
Adnan
  • 329
  • 3
  • 9
14
votes
3 answers

Typography of multi-letter variables

Chemical elements are typeset with upright font ($\ce{H2O}$ for water) while variables are typeset with an italic font ($V$ for volume). But is there a convention what to do with multi-letter variables like IC50, EC50 (or others without subscripts)?…
mhchem
  • 3,316
  • 2
  • 16
  • 34
12
votes
1 answer

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? Is this really a bond? Is this a short form for…
mhchem
  • 3,316
  • 2
  • 16
  • 34
12
votes
5 answers

What is the difference between O & O2

What is the difference between $\ce{O}$ and $\ce{O2}$. If C is carbon and then why $\ce{O2}$ is oxygen.
roxaite
  • 295
  • 1
  • 3
  • 6
12
votes
2 answers

What is the role of the slash ("/") in chemical reactions?

I have always been confused about the role of slash in chemical reactions. In some reactions, e.g. $\ce{NaBH4}/\ce{OH-}$ it means we use both compounds, right? And in reactions where we write $\ce{Pt/Pd/Ni}$ do we mean platinum or palladium or…
geek101
  • 1,041
  • 5
  • 15
  • 24
11
votes
3 answers

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, it makes sense, since you could argue that if a set amount…
Nefeli
  • 141
  • 6
10
votes
1 answer

Is there a convention for breaking chemical formulae across lines?

I found a chat where a user asked for chemical formulae to be broken across lines (with LaTeX/mhchem). I could imagine offering a switch to allow this. But only, if line-breaking within formulae is not completely uncommon. According to him/her,…
mhchem
  • 3,316
  • 2
  • 16
  • 34
10
votes
1 answer

Syntax and Typography of Atomic Orbitals

For mhchem (i.e. the \ce command you use here), I want to improve the support for atomic orbitals. (Reason: I see it quite often used here.) But only a few things about orbitals are mentioned in IUPAC documents. Many more seem to be "unwritten…
mhchem
  • 3,316
  • 2
  • 16
  • 34
1
2 3 4