Order of atoms in molecules

[Ryan Chang 1C]

Is there a specific order atoms have to be in? For example, in glucose, how do we know that carbon comes first, then hydrogen, then oxygen.

[kevinchang_4I]

Hi Ryan, usually the larger atom will go first, at least that's what my TA said. He also said it is not crucial to know at the moment, and most of the time it is given.

[Ami_Pant_4G]

After some research, I found out that if carbon is present in the molecule, it is written first. Hydrogen is usually written second, if/when carbon is present. The rest of the elements are written in alphabetical order there after. Despite this, my TA told us that it doesn't really matter right now so I would not worry about it too much. Hope this helps.

[preyasikumar_2L]

It usually doesn't really matter what order the elements are in a compound, as long as the subscripts are correct. According to the Hill system, in compounds with carbon and hydrogen, you typically write carbon first, and then hydrogen, and then the remaining elements in alphabetical order. Another source says that if carbon and hydrogen aren't present, then in ionic compounds write the metal first and then the nonmetal (or cation and then anion), and in molecular compounds write the elements in order of increasing electronegativity. I'm not 100% sure on element order in compound conventions though, but it doesn't matter too much. Hope this helps!

[stephaniekim2K]

Like most people said already, the order is not very important, but there is a method called the Hill System that states that Carbon atoms are listed first, then Hydrogen, and the rest of the atoms alphabetically.

[ahuang]

If carbon is in the molecule, it is usually written first, and hydrogen is second. For now, I think we just need to know that hydrogen and metals come first and nonmetals are second.

[rohun2H]

My TA said that it may be ordered in any way and will still be an acceptable answer, at least for now.