Talk:Chemical formula

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chemical/molecular/empirical formula[edit]

The article on Empirical Formula equates "chemical formula" with "empirical formula," and distinguishes "molecular formula"

The article on Chemical Formula equates "chemical formula" with "molecular formula" and distinguishes "empirical formula"

(There is no separate article on "Molecular Formula")

So who is right?

Structural formula[edit]

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)Reply[reply]

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)Reply[reply]

Inorganic compounds[edit]

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

  • Al2(SO4)3 · 16 H2O
  • FeIII

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)Reply[reply]

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

Electronegativity-based alternative to Hill system ordering[edit]

I studied chemistry, and I definitely learned the Hill system: First carbon, then hydrogen, then all other elements in alphabetical order. However, I was taught (and I often observe) a slightly different system. Like Hill, it begins with carbon then hydrogen. Unlike Hill, all other elements are in order of electronegativity, with fluorine last. This gives the familiar H2SO4, whereas Hill gives the far less common H2O4S. Wikipedia itself often favors this electronegativity-based system, as can be seen in halogenated compounds where Br and Cl appear at the very end, despite coming early in the alphabet. I think Hill is favored when electronegativity is not so obvious. On a related note, ionic compounds generally get the cation first, which obeys the electronegativity order but overrides the precedence of C and H, giving familiar ionic compounds like NaCl, NaOCl (which is not in Hill order), HCl (not Hill order because it lacks carbon but H precedes Cl), and NaHCO3 (sodium bicarbonate, showing that C loses primacy in an ionic compound). I don't know if there are names for these systems that use electronegativity to partially or fully override alphabetical order. They also seem less standardized than the Hill system, but quite common. (talk) 11:03, 29 October 2023 (UTC)Reply[reply]