Chemical compound names

Ok, this is probably a stupid question but one that is bugging me.

How do you decide how to write out a chemical compound name? In a project a coworker is doing it is written out H₂O and in another section it is written OH₂. Is there a particular order to what chemical comes first? Is it by group?

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How do you decide how to write out a chemical compound name? In a project a coworker is doing it is written out H2O and in another section it is written OH2. Is there a particular order to what chemical comes first? Is it by group?

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I have never seen water written out as OH₂. In organic chemistry (and in The Merck Index) the order is always C, H, O. For example, glucose is C₆H₁₂O₆. My only guess is that there were two alcohol groups which were listed as (OH)₂ which would describe a protonated carboxy group (IIRC, organic was so long ago).

I've seen it written both ways, but it is usually H20. Most of the time I've seen it written as OH2 are when the connectivity of the bonds is shown. Such as CH30H2. That would be a protonated methanol. When writing the mechanism for this reaction, I think water is usually written as 0H2 so that its oxygen is oriented towards the carbon of which is will eventually bond. Ex.

CH3Cl + OH2 --> CH3OH2 + Cl ---> CH30H + HCl

Either way, it's convention, since the empirical formula and structural formula are identical. I think for the empirical formula H is before O, but if it's written structurally I think it can be oriented any way the author wants if it illustrates a mechanism better.

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I think for the empirical formula H is before O, but if it's written structurally I think it can be oriented any way the author wants if it illustrates a mechanism better.

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I think that hits the nail on the head. You are given much more lee way when relating structural relationships.

and H₂O doesn't really address the issue of what is really going on, but presents a really simplified version.

in practice there is a sea of H^- and OH⁺ as well as chains of {H₂O}_n and a variety of energy levels, and ...

... I also think I have seen it as HOH (hydroxylic acid? :D)

{added by edit} isn't it interesting that water combines the elements of acids and bases ...? a yin\yang compound?

This message has been edited by RAZD, 03-04-2005 23:39 AM

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we are limited in our ability to understand
by our ability to understand

RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

I've seen H2O and HOH both in professional chemistry writings - which depends on whether the author want to emphasize exactly that yin/yang thing you mention, RAZD. And that ability to be both an acid and a base, while also being a solvent, is sure 'nuff fairly unusual. Anhydrous ammonia and hydrogen fluoride can do it, but I'll normally pick water over either of those.

{added by edit} isn't it interesting that water combines the elements of acids and bases ...? a yin\yang compound?

.....and the elements conducive to combustion, hydrogen and oxygen which H2O, is often used to extinguish.

makes one wonder about the emphasis on carbon based life rather than water based?

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we are limited in our ability to understand
by our ability to understand

RebelAAmerican.Zen[Deist
{{{Buddha walks off laughing with joy}}}

yes, I don't mind a little branch in my scotch, but that's as far as I'm willing to go. :D