Seems like someone has gone on a bizarre edit spree, deciding to randomly change $K_4[Fe(CN)_6]$(K_4[Fe(CN)_6]) to $\ce{K4[Fe(CN)6]}$(\ce{K4[Fe(CN)6]}) (with no other edits). This is purely a matter of stylistic choice, and I find it really annoying to have some questions bumped for just this.

Should such edits be discouraged? (I think so.)

From typographical point of view, the question whether atoms in a formula are upright or italic is not clear at all, it varies from author to author, from sub-field to sub-field and from journal to journal. Therefore I think that we should not unify the style across the site and rather leave it to the authors.

And no matter what, editing K_4[Fe(CN)_6] into \ce{K4[Fe(CN)6]}, as well as adding the thin space, it all certainly qualifies as a minor edit.

This \ce was just introduced to offer more convienieneineice in rather typing _ and other such symbols again and again. but conside the case of separated mention of \ce{Ca} and \ce{HCl} or \ce{H_2SO_4}. in the first case instead of offering convinience it is more annying to type whlole \ce and the two braces {,} Same goes for second and it might be useful in third case or longer names but after all it should be left to the author.

Some people have misunderstood that as the site supports it, it is rule to use this, but this not the case so and such edits should be avoided, as I think.

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    $\begingroup$ Chemical formulas do not adopt an italicized format in professional, scientific journals. Sending a manuscript out with such a style would result in reviewer comments stating that it must be fixed. Here at Chem:SE it would be prudent to adopt such formalism as well. The edits are useful and not harming anyone. $\endgroup$ Commented Nov 8, 2014 at 15:21
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    $\begingroup$ If you're talking about this one I edited yesterday (first answer), I probably wouldn't have bothered if it weren't in the mathcal font (which takes more writing than \ce, even), which stands out dramatically and has some crazy letter shapes and weird kerning. $\endgroup$ Commented Nov 8, 2014 at 17:31
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    $\begingroup$ @ADG Clearly you have the time to post a question for which you've accepted your own [rather incorrect and poorly worded] answer so why not just simply format chemical formulas the proper way? $\endgroup$ Commented Jan 26, 2015 at 20:20

3 Answers 3


Unfortunately for your argument, it is very, very clear how one has to write chemical formulae. The International Union of Pure and Applied Chemistry (IUPAC) has written a whole book about that, called the Green Book. Its official title is Quantities, Units and Symbols in Physical Chemistry.

You may now think that it is not such a big deal, but it really is. You might have a look at one other post on meta (shameless self-advertisement here). So yes, please edit every question you see that uses wrong styles, because there is a correct way to do it and only by showing it to everyone do they realize their erroneous ways.

I also quickly want to demonstrate the difference between the two forms that you give: $$ K_2[Fe(CN)_6] $$ This is clearly a function(-al) $K$ (with index $2$) of a variable $F$ and a function $e$ (index $6$) of the variables $C$ and $N$.

$$ \ce{K2[Fe(CN)6]} $$ This is the chemical formula for potassium hexacyanoferrate(IV).

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    $\begingroup$ i was talking about using \ce or not on this site, maybe youmisunderstood and i can't seem to understand your post too $\endgroup$
    – RE60K
    Commented Nov 8, 2014 at 12:24
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    $\begingroup$ @eaxdpiotnyeantial I'll try to explain in further detail: Using \ce helps me avoid writing $\ce{H2O}$ as \text{H}_2 \text{O} but simply as \ce{H2O}. Also, element names are never cursive in a chemical formula. $\endgroup$
    – tschoppi
    Commented Nov 8, 2014 at 13:24
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    $\begingroup$ but does it matter on this site? what's the benefit, so that i would use that both are perfectly clear here and i dont think doesnt even matter $\endgroup$
    – RE60K
    Commented Nov 8, 2014 at 13:28
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    $\begingroup$ Well, my entire argument (see my answer above) rests on the point that we should try to be as correct as possible at all times. So even if both types are clear, one is correct and one isn't, and as such one should be given the preference at all times. $\endgroup$
    – tschoppi
    Commented Nov 8, 2014 at 13:29
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    $\begingroup$ i don't think we need to be so nitpicky everytimes,actually who did decide that it is the only correct thing on this site $\endgroup$
    – RE60K
    Commented Nov 8, 2014 at 15:06
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    $\begingroup$ As a scientifically oriented community it seems obvious that we try to emulate as many standards as possible. One of which being the correct writing of formulae. It was therefore "decided" by IUPAC how formulae are written on this site. If you have a problem with it, feel free to write a letter to them. $\endgroup$
    – tschoppi
    Commented Nov 8, 2014 at 23:39
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    $\begingroup$ i didnt knew iupac decided something for this site $\endgroup$
    – RE60K
    Commented Nov 9, 2014 at 6:12
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    $\begingroup$ On another note, the indices in the mathematical environment $...$ do not align properly on the same baseline (because it is not necessary for a mathematical formula) and the top/bottom spacing is also not quite right. The mhchem environment \ce{...} fixes this. $\endgroup$ Commented Nov 12, 2014 at 2:16

To follow tschoppi's answer with a simpler example:

What is the difference between $\ce{P}$ and $P$? Which one do we take to mean phosphorous and which to mean pressure. I know that some folks prefer $p$ for pressure, but I can make a similar case for a whole host of letters that serve double duty in science. Since IUPAC recommends that chemical symbols use plaintext, we can reserve the "italics" or emphasis style for physical and chemical quantities, functions, variable, etc.

The goal is to communicate clearly. Within a chemical formula, you may gather by context whether $K$ is potassium or not, but without that context, or without formatting cues

  • $A$ = face-centered on A faces (Bravais lattice)
  • $B$ = boron, magnetic field, face-centered on B faces (Bravais lattice)
  • $C$ = carbon, capacitance, cysteine, face-centered on C faces (Bravais lattice)
  • $F$ = fluorine, farad (unit of capacitance), Faraday's constant, force, phenylalanine, face-centered Bravais lattice (A, B, and C faces)
  • $H$ = hydrogen, magnetic field intensity, enthalpy, henry (unit of inductance), histidine
  • $I$ = iodine, ionic strength, moment of inertia, isoleucine, electric current, luminous intensity, identity operation/matrix, body-centered Bravais lattice
  • $K$ = potassium, kelvin (unit), equilibrium constant, lysine
  • $N$ = nitrogen, newton (unit), asparagine, normality, neutron number, number of [things]
  • $O$ = oxygen
  • $P$ = phosphorous, power, pressure (sometimes), proline, potential energy, primitive Bravais lattice
  • $R$ = rhombohedral Bravais lattice
  • $S$ = sulfur, entropy, seimens (unit of conductivity), S absolute configuration of chirality, serine
  • $U$ = uranium, internal energy,
  • $V$ = vanadium, volt (unit), voltage/potential (usually), volume
  • $W$ = tungsten, work (sometimes)
  • $Y$ = yttrium, tyrosine, yotta (SI prefix)

And of course to add to the confusion, most of the rest of the alphabet can be used to refer to placeholder/generic elements in chemical formulas.

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    $\begingroup$ oh I think you are very vague, boron and magnetic field! carbon and capacitance!tungsten and work! and many more, even if you wish to hide the context, one can easily differentiate even between such examples. $\endgroup$
    – RE60K
    Commented Dec 12, 2014 at 7:42
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    $\begingroup$ So, then, what is the difference between $\Delta H$ and $\Delta \ce{H}$? Is there? Which one is the change in enthalpy? What is the other one? The aim of good scientific and mathematical notation is to be as precise as possible. $\endgroup$
    – Ben Norris
    Commented Dec 16, 2014 at 1:42
  • $\begingroup$ to me both look like change in enthalpy because none of them is used in maths afaik, none of the sites that come up on google search "enthalpy" use $\Delta \ce{H}$ $\endgroup$
    – RE60K
    Commented Dec 16, 2014 at 4:02
  • $\begingroup$ Excellent points in terms of a simple way to differentiate between chemical symbols and measures. $\endgroup$
    – user15489
    Commented Apr 19, 2015 at 7:30

The basic difference is chemical formulae should be non-italic and mathjax uses italic fonts for default, which some people don't like and can't differentiate given or not the context. Seems like you have to follow the majority.


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