Talk:Chemical formula/Archive 1

Archive 1

Missing information

I'm missing mentioning of other (more advanced) ways of describing chemicals, such as IUPAC nomenclature, or visual representations, as for example File:Flutamide.gif (how do you actually call these diagrams?). --Abdull 17:06, 6 December 2005 (UTC)

Those are usually called "structure diagrams". Itub 23:55, 2 January 2006 (UTC)

Ax2

um.... i wanted to know how to a write a chemical formula for given elements correctly. i know about the ratio method but it doesnt work with non- metals and non - metals. — Preceding unsigned comment added by 69.199.61.67 (talk) 15:11, 6 January 2006 (UTC)

Question

What does a formula such as FeS_2-x mean? Can this be included in the article?

See Non-stoichiometric compound. Yes, I think it should be mentioned in the article. Itub 16:07, 9 February 2006 (UTC)

Thanks ;)

chemical reaction

Do the groups of chemical equations Ch3OCH3, Ca3(PO4)2,CO2,H2CO3 contain entirely of organic compounds?

No. DMacks 16:06, 4 May 2006 (UTC)

Mystery Symbol

in a number of chemicle composition formulas, I've encountered a symbol before the equation that looks like the infinity symbol with half of the second loop sliced off, or an 'o' and a 'c' pushed together. I am wondering what exactly this symbol means in reference to the equation. I've not encountered it anywhere else before.

e.g- Goethite: 'oc' - Fe⁺³O(OH)

Sounds like the "proportional to" sign (∝). Maybe it's used to indicate a non-exact formula representation (correct chemical formula, but actual allotrope or mineral form not completely represented), but I'm only hypothesizing here. DMacks 02:43, 3 January 2007 (UTC)

Order

In which order are elements in the chamical formula ordered? --Artman40 12:32, 9 January 2007 (UTC)

There are many different conventions. One of them is the Hill system, which is basically alphabetical and which is useful when you have a long list of compounds that you want to sort (for an index, for example). In other cases people sometimes sort by electronegativity (for example, in salts and other binary compounds; it is more common to see NaCl than ClNa), and in others people write the formula in a way that suggests the structure of the compound (especially for small organic molecules, such as CH3OH). Itub 16:44, 9 January 2007 (UTC)

I think that there should be a section about that in the article. --Artman40 17:49, 10 January 2007 (UTC)

naming elements in formulae?

how are chemical formulae read in english? for example, water is [eich 2 oh], and what about iron - [fe] or [aien]?

Iron is just iron. for example, FeO is just iron two oxide. (It has to do with chemical nomenclature, also.) 75.5.10.153 23:08, 16 September 2007 (UTC)minidude09

R

Some articles like keytone and functional group follow the standard practice of using "R" (sometimes with subscripts) to represent arbitrary structures. This practice should be explained in this article including why "R" is the symbol chosen and what it stands for. (Radical (chemistry)?) I've added the same note to Talk:Structural formula. -- Beland (talk) 16:14, 19 April 2008 (UTC)

Berzelius' name

The name "Jöns" is not spelt with an "o", but with an "ö". The two letters are not equivalent in Swedish and have completely different pronunciations, hence the "Jons" is a misspelling of the name. The article on Jöns Jakob Berzelius spells the name correctly and I have pursuant to that corrected the spelling in this article. It should thus not be reverted back to "Jons" as was done previously. Fassitude (talk) 23:50, 15 June 2008 (UTC)

Your first edit was reverted by a vandal fighter using an automated tool. Your edit probably triggered this because it had no edit summary (plus you were editing anonymously). Something as simple as "linkfix" or "correct name" would have prevented this :-) Cacycle (talk) 00:29, 16 June 2008 (UTC)

Should we have a notice about unsubscripted numerals in formulae?

I find it quite distressing, now that subscripting and superscripting are so easy in any decent HTML editing environment, to see barbaric forms such as "CO2" and "H2O". (I have even seen "H20" -- H-twenty!) My hope is that this article could discourage such usage. When composing text in an ASCII environment, one might use such a form as "H_2O", which I have seen occasionally.

I suspect that in-line forms are a consequence of general public ignorance of chemistry, combined with a rather dismal typical level of real literacy (I don't mean ability to read and write at 6th grade level) among native English speakers. As an aside, a Boston tank truck that delivers liquefied CO₂ is prominently marked "Co₂" — "dicobalt"! Truck lettering is not particularly literate in the USA, at least in the Northeast. Regards,Nikevich (talk) 01:41, 25 July 2010 (UTC)

What are numeric subscripts called?

I've been trying to learn the formal name for the numeric subscripts in chemical formulae, such as the "2" in "H₂O". I had hopes that this article would have this information, but, no luck. It it possible that there simply is no formal name? I was thinking "valence coordination [number]", but that is most likely to be incorrect.Nikevich (talk) 01:41, 25 July 2010 (UTC)

Number of atoms?--Wickey-nl (talk) 08:42, 25 July 2010 (UTC)

Other forms I see on the net...

I am uncertain how to read these formulas...

• Is the bracket similar to the paranthesis? ie. [B₁₂H₁₂]^2-.
• At symbol, "@", ie. [As@Ni₁₂As₂₀]^3-

Thanks, CarpD 23:58, 23 October 2007 (UTC)

Brackets are customary to enclose a grouping which has an overall charge, as [B₁₂H₁₂]^2-. Parentheses are customary to enclose a grouping which occurs more than once in the formula, as Fe(NO₃)₂. Also parentheses can be nested inside brackets, as [Co(NH₃)₆]³⁺

And @ means that the As is trapped inside the Ni₁₂As₂₀ cage, but not chemically bound to it. This notation became popular with the discovery of fullerene cages, which can trap atoms to form La@C₆₀ for example.

These points could be included in the article. Dirac66 00:50, 24 October 2007 (UTC)

Thanks for the information. That helped a lot. But yeah, I think that would most definitely be in the article. Or, in this article, Structural formula? Thanks, Marasama (talk) 06:38, 22 November 2007 (UTC)

using this article tyou should use this article because it is important on your lesson because its all about compound and thats all thank you —Preceding unsigned comment added by 180.194.1.228 (talk) 09:42, 27 September 2010 (UTC)

I have added both points to this article on 8 January 2008. Dirac66 (talk) 22:45, 13 January 2008 (UTC)

Homework help

determine some example of atoms in the followig formula nac1,

— Preceding unsigned comment added by 71.252.44.236 (talk)

This would be a question for Wikipedia:Reference desk/Science, but the Reference Desk wants students to do their own homework. -- Beland (talk) 16:17, 19 April 2008 (UTC)

As well, it's important to use capital and small (Unicode term) letters correctly. I surely hope the student made a few mistakes in transcribing the question, though. If exactly transcribed, there's cause for worry. (In particular, "mb" in computer technology signifies millibits, which don't exist in any ordinary discussion. However, "mHz", millihertz, is a legitimate unit of measurement for quite-low frequencies.) Substituting an "l" (small L) for a numeral '1' has not been necessary once typewriters became rare. (Woops, was logged in, but no more. User Nikevich, who uses DHCP.)

74.104.151.42 (talk) 11:51, 15 December 2011 (UTC)

Further Explanation Needed

I put after the second paragraph of the ions section, since it only says that sometimes you use brackets, and nothing about what they do. I still have no clue what brackets do. Njaohnt (talk) 18:06, 3 November 2012 (UTC)

It's not explained in best way, but brackets are often used in ionic formulae to isolate and set off the ionic species, especially when they are complicated ones. The ligand (atom or group of atoms) inside the brackets has one or more charges, positive or negative, and will act like a single charged species. If the compound is melted, each thing inside the brackets can be expected to swim around independently as a charged polyatomic ion, with the atomic attachments (covalent or semicovalent coordination bonds) inside the brackets, all still in place, holding it together. The same when the compound is dissolved in a liquid, if it can be. Also, the things in brackets tell how the compound can be made, out of other salts.

A complication is that for simple polyatomic ions, they leave the brackets out, as they are understood. Thus, you could in theory write [NH₃][NO₃], but nobody ever does. However, for complicated ions, you see it's helpful to write ferric ferrocyanide as Fe₄[Fe(CN)₆]₃, which tells you it can be made from potassium ferrocyanide and any ferric salt, rather than writing Fe₇(CN)₁₈, which doesn't help at all.SBHarris 02:13, 4 November 2012 (UTC)

Not all chemical formulas are molecular formulas

The lead now says that chemical formulas are also called molecular formulas. Wrong. Table salt is certainly not composed of NaCl molecules, but NaCl is its chemical formula. Sodium chloride has no molecules, and so it cannot have a molecular formula. Molecular formulas are one subtype of chemical formulas, and since most chemical compounds don't actually consist of "molecules" (the crust and mantle of planet, for example), that's a good thing. Minerals are usually written as ionic formulas if that is possible, and these are usually limited by the number of species it takes to write out the unit cell of the mineral. For example, look at the many ionic formulas in the silicate minerals. Some of these are network solids that are long polymers of silicon and oxygen, with cations going along. Others are not. But most of them can be written with ionic condensed formulas that tell us more than empirical formulas do. Finally, however, empirical formulas, homely as they are, are one type of legitimate chemical formulas (even though they are not molecular formulas, either). Empirical formulas say less about structure than molecular or ionic formulas do, but they are still chemical formulas.

The article does a fair job of discussing these subtypes of chemical formulas, but the lead doesn't do a good job of breaking them out and preparing us for what comes later. Also, the lede didn't note the difference between a chemical formula (which is a line of symbols, although it can be condensed to suggest some simple structure) and a full structural formula (which is a graphical object). So the lead needs some rewrite. If nobody objects, I'll take a shot at it, but am writing here to forestall cries of outrage at a big lead change. However, think about it. SBHarris 02:46, 4 November 2012 (UTC)

Hill system

Interesting. The edit is correct, but the editsummary is wrong [1]. (in short: if the formula is not empirical, Hill should not be used. 'Not empirical' is: the formula shows extra, structural info like groups). Still: the edit is OK. -DePiep (talk) 21:12, 27 June 2016 (UTC)

Subscript ambiguity

I edited Chemical formula § Isotopes, using {{Nuclide}} to render ¹⁶
₈O
₂ with the superscript above the subscript prefix, I realized that the suffix subscript refers to either the number of atoms (2 in this case) or the number of neutrons (as assumed by {{ComplexNuclide2}}). Does this ambiguity need to be addressed or did I miss something? @DePiep? —[AlanM1(talk)]— 23:16, 29 July 2018 (UTC)

For chemical use the "8" should be omitted. Isotopomer formula normally have the style ¹⁶O₂. The atomic number or neutron number can be calculated if desired, but is not as relevant as knowing it is oxygen, but a specific isotope. Graeme Bartlett (talk) 02:34, 1 August 2018 (UTC)

So that means we should remove the paragraph starting with A left-hand subscript is sometimes used redundantly to indicate the atomic number.? —[AlanM1(talk)]— 14:07, 1 August 2018 (UTC)

No, it should stay, as it is true. Yilloslime (talk) 20:21, 1 August 2018 (UTC)

The left subscript may be significant for nuclear reactions, but is unimportant for chemical reactions. Petergans (talk) 21:08, 1 August 2018 (UTC)

Are there situations where "O" does not mean "8" (ie Z=8)? Writing ₈O is redundant (and informative, as we do in the infobox here). - DePiep (talk) 03:18, 7 August 2018 (UTC)

What I'm getting at is the right subscript (2), which is ambigous, meaning either 2 atoms of oxygen or 2 neutrons (in one atom). It therefore seems wrong to say that the left subscript is sometimes used with dioxygen (O₂) since you would not normally do this because of the ambiguity – ₈O₂ meaning either two atoms of oxygen or oxygen-10 (¹⁰
₈O
₂ with 8 protons and 2 neutrons, which I'm guessing doesn't "exist", though ¹⁶
₈O
₈...). I get that it can usually be gleaned from the context, but shouldn't we warn of the potential conflict? The section isn't sourced, but it would seem like something that would be mentioned if it were.

I'll note that all the examples in the nuclear reaction article avoid the right subscript altogether. In one case,

6 3Li

+

2 1H

→

2 4 2He

two atoms of helium are instead indicated by the "2 " in front. —[AlanM1(talk)]— 23:47, 1 August 2018 (UTC)

I get that it can usually be gleaned from the context, warn of the potential conflict: better, do not use that second meanng of right-sub suffix. Use the isotope left-superschript, and the number of neutrons is not needed (is implicit). - DePiep (talk) 03:42, 7 August 2018 (UTC)

Do we have a ref that suffix-subscript is used for number of neutrons? Our Symbol (chemistry) article doesn't mention it, nor does Isotope#Notation. But while we're talking notational ambiguity, prefix-superscript can mean either isotopic mass-number (¹H-NMR) or spin-state (singlet oxygen is ¹O₂). I can't think of any actual cases where the meaning is not clear (no masses low enough or spins high enough to have an actual crossover). DMacks (talk) 06:37, 2 August 2018 (UTC)

Red Book? (first hit is p. 47 (53/377 in pdf) is about "Indication of mass, charge and atomic number using indexes (sub scripts and superscripts)". with example ¹⁶
₈S²⁺
. - DePiep (talk) 16:19, 6 August 2018 (UTC)

Looks like we could always use brackets (¹[O₂]) or a more complete term-symbol (¹Δg O₂) if there were possible confusion. DMacks (talk) 03:48, 7 August 2018 (UTC)

Back from the start OP: where has been defined that the subscript "2" in ¹⁶
₈O
₂ represents number of neutrons? And is there any practicval use for using it? So far, only or own {{ComplexNuclide2}} does so without reference.

Also note that the number of neutrons is derived (calculated) from the meaningful isotope description: ⁸O has 2 neutrons because N = A − Z. {{ComplexNuclide2}} does this calculation. So that number is both redundant and confusing. -DePiep (talk) 03:34, 7 August 2018 (UTC)

Only use I can envision is in nuclear reactions, to emphasize what changes. For example, in alpha decay, we lose "2 protons and 2 neutrons" rather than having to recognize that "lose 2 protons and 4 mass units" means 2 neutrons were lost. Likewise for beta decay or electron capture, plainly stating that the numbers of p and n change. But if we're just making this up ourselves for convenience, no matter how "useful" or well-intentioned we might think it is in some context, WP:V says no. My gen-chem textbooks are all in a box at the bottom of a pile right now:( DMacks (talk) 03:46, 7 August 2018 (UTC)

(ec) I may be confused about the confusion, but I have never ever seen a subscript to the right of a chemical symbol denote anything other than the number of atoms in a compound, so don't see how there is any possible ambiguity over what ¹⁶
₈O
₂ represents. It's certainly not a common or accepted use in current chemical discourse, though I suppose it could be used in other fields or maybe it was used in the past? Yilloslime (talk) 03:53, 7 August 2018 (UTC)

Over at Template talk:ComplexNuclide2, creator SkyLined replied to my little note. No source from there either. Three articles use the template. - DePiep (talk) 14:54, 7 August 2018 (UTC)

¹⁶
₈O
₂ is unambiguous. The notation ²³⁵U and ²³⁸U distinguishes between isotopes. Formulae like P₄ distinguish between allotropes. The prefix subscript, signifying atomic number is not needed in chemistry, it only needed with nuclear reactions Petergans (talk) 16:14, 12 August 2018 (UTC)

@Petergans: That is the implication of having a template that does this, but do you have a reference that shows this notation (with all three numbers, or at least the pre-super and post-sub), preferably being used in a (nuclear) reaction? —[AlanM1(talk)]— 22:00, 12 August 2018 (UTC)

I thought we are looking for a source that says the post-subscript is number of neutrons. Other notation parts are not disputed nor ambivalent. -DePiep (talk) 22:53, 12 August 2018 (UTC)

We're on the same page. I'm assuming (perhaps incorrectly) that O₂ by itself would never be used to indicate 2 neutrons, because it's just too ambiguous. At least if there's also the "weird-looking" subscript prefix (i.e. ₂O₂), the reader might be clued in that it could be a nuclear reaction and that the subscript suffix might mean something other than 2 atoms. —[AlanM1(talk)]— 23:04, 12 August 2018 (UTC)

In the Template:ComplexNuclide2 documentation, the post-subscript refers to "complex nuclide", a term I have never seen used. Looking at the template documentation, section examples, there is no indication of where the right subscript came from.

The number of atoms in a molecule as in {{Nuclide|O|16}}₂}} (rendered as ¹⁶
₈O
₂) is not part of the template.Petergans (talk) 09:27, 13 August 2018 (UTC)

• Conclusion: I read a clear consensus that the post-subscript motion is not to mean "number of neutrons" in any way. No supporting RS documentation was brought forward for this, most if not all contributors to this thread have not known or seen that usage, and the GF creator of {{ComplexNuclide2}} (talk) has also noted along this line [2]. We shall not use that notation on this wiki, and I will remove it from that template & articles. - DePiep (talk) 10:18, 13 August 2018 (UTC)

 Done. {{ComplexNuclide2}} does not show number of neutrons any more. Added: |q= for number of atoms (checical formulae). See also /testcases- DePiep (talk) 11:24, 13 August 2018 (UTC)

Well done. I implemented {{ComplexNuclide2}} at Chemical formula § Isotopes and also added brackets to the example in the first 'graph there (if someone could make sure that's right please). I updated the doc to show that |q= is available in {{ComplexNuclide2}} as well. —[AlanM1(talk)]— 23:14, 13 August 2018 (UTC)

Semi-protected edit request on 4 March 2020

I believe I found a citation needed. I also agree with the tag. The last sentence seems like opinion. None of the information I came across said anything about this breaking rules.

The alkene called but-2-ene has two isomers, which the chemical formula CH₃CH=CHCH₃ does not identify. The relative position of the two methyl groups must be indicated by additional notation denoting whether the methyl groups are on the same side of the double bond (cis or Z) or on the opposite sides from each other (trans or E). Such extra symbols violate the rules for chemical formulas, and begin to enter the territory of more complex naming systems.^{[citation needed]}

The alkene called but-2-ene has two isomers, which the chemical formula CH₃CH=CHCH₃ does not identify. The relative position of the two methyl groups must be indicated by additional notation denoting whether the methyl groups are on the same side of the double bond (cis or Z) or on the opposite sides from each other (trans or E). BobTheMan 03:01, 4 March 2020 (UTC)

Done today. Dirac66 (talk) 22:49, 7 March 2020 (UTC)

References

Chemical full form

Try to solve 2402:3A80:1597:AC85:987B:D7FE:29B3:4AA4 (talk) 06:33, 4 February 2022 (UTC)

Structural formula

A quick web search shows that structural formula is usually considered to be a type of chemical formula. The top section of this article currently says that it is not, which I believe to be incorrect. I have added a short subsection Structural formula (with a source) into the section Types, but I am not sure I can modify the lead section well. I would like to hear more opinions anyway. Petr Matas 11:43, 23 June 2022 (UTC)

I, a relative layperson, definitely expect all [specifier] formulas to be a chemical formula indeed. Als. I hope this articel can give a compreshensive overview. Currently, not all types are evenly descxribed. I see:

chemical formula: structural formula, empirical formula, molecular formula, condensed formula, condensed molecular formula aka "semi-structural formula", (plus Hill form).

So: I support. -DePiep (talk) 12:12, 23 June 2022 (UTC)

Inorganic compounds

What type of formula is the one typically used for inorganic compounds? For example:

• Al₂(SO₄)₃ · 16 H₂O
• Fe^III
  ₄[Fe^II
  (CN)
  ₆]
  ₃

It is neither a molecular formula, because it groups atoms into anions, cations and complexes, nor a structural formula. It looks similar to the condensed formula, but it does not show how the anions and cations are connected, only their numbers. How do we call this type of formula? Petr Matas 12:29, 23 June 2022 (UTC)

It's similar to a condensed formula. DMacks (talk) 15:58, 23 June 2022 (UTC)