Talk:Chemical formula

chemical/molecular/empirical formula

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?

Electronegativity-based alternative to Hill system ordering

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. 209.6.225.254 (talk) 11:03, 29 October 2023 (UTC)

Hill order

Following the rules of the Hill system, BrClH2Si should be sorted before BrI, because Cl < I. The priority of single-letter over two-letter symbols only applies to the same letter (C < Cl, I < In). This can be confirmed since Hill's original publication sorts CCuN … < ClCu … < KMnO4. Aerilius (talk) 19:00, 2 January 2024 (UTC)

 Fixed Thanks for catching that! DMacks (talk) 19:40, 2 January 2024 (UTC)