is water is hydrogenated oxygen?

[lemur]

I was wonder if experienced chemists tend to think of molecules in terms of dominant and subordinate parts. For example, hydrogen seems to be almost like chemical filler in many compounds, such as when carbon forms chains or combines with other elements with hydrogen filling in the rest. Is it correct to call water "hydrogenated oxygen," or methane "hydrogenated carbon?" By thinking like this, it gives me the idea that such compounds can be understood in terms of a dominant element, e.g. oxygen or carbon. That way, it seems like you could look at natural processes involving these compounds as essentially interactions of the dominant elements. E.g. when I think of rust and water, I usually think of those in terms of iron and hydrogen because that is the first element in the chemical names, but couldn't you also think of those as two variations of oxygen and compare them in terms of variation in the behavior of oxygen-based compounds? I hope you see what I'm getting at here. I'm trying to look for different ways to approach chemistry to see things in a different way, for whatever innovative effects it might have to do so. Maybe some people already think like this, though.

[mississippichem]

I was wonder if experienced chemists tend to think of molecules in terms of dominant and subordinate parts. For example, hydrogen seems to be almost like chemical filler in many compounds, such as when carbon forms chains or combines with other elements with hydrogen filling in the rest. Is it correct to call water "hydrogenated oxygen," or methane "hydrogenated carbon?" By thinking like this, it gives me the idea that such compounds can be understood in terms of a dominant element, e.g. oxygen or carbon. That way, it seems like you could look at natural processes involving these compounds as essentially interactions of the dominant elements. E.g. when I think of rust and water, I usually think of those in terms of iron and hydrogen because that is the first element in the chemical names, but couldn't you also think of those as two variations of oxygen and compare them in terms of variation in the behavior of oxygen-based compounds? I hope you see what I'm getting at here. I'm trying to look for different ways to approach chemistry to see things in a different way, for whatever innovative effects it might have to do so. Maybe some people already think like this, though.

 

You can think of it that way, but I'm not sure if you'll see any advantages by doing so. You can group compounds into families but it is only arbitrarily useful. You can think of ethane, propane, butane, pentane... as polymers of methane, but it really doesn't make much difference.

 

 

I can think of this molecule as a carboxylic acid derivative of benzene or conversely a phenyl-substituted methanoic acid. The reaction to get to this molecule would be the same either way, regardless of which molecule I call the substrate. Personally, I usually call the larger fragment the substrate.

 

As far as naming goes, there are IUPAC (international union of pure and applied chemistry) conventions that are supposed to be used for that. Most people follow them, though some common molecules have slang terms like water; which is technically dihydrido oxygen by inorganic naming convention.

[Horza2002]

You can think of water in that way yes...and for water that is a reasonable way of thinking of it...only look at the oxygen.

 

However, only considering the reactivity of molecules with respect to the heteroatoms doesn't always work. For example, if you alkylate a terminal alkyne by deprotonating it and then reacting it with a alkyl bromide, there are no heteroatoms involved (ignoring the bromide).

 

Although, on the other side of the coin...alot of intertactions between molecules DOES depend on the heteroatoms present (e.g. hydrogen bonds).

 

I think what you have there is just a slightly different angle on the "norm"

[lemur]

Thanks for your posts, MC & HZ. They give me new material to think about. What I'm trying to do is get to a more intuitive sense of how matter behaves in and as chemical compounds. MC, you say that grouping them into families doesn't make a difference but I'm not so much thinking of just classifying them but rather looking at molecules in terms of dominant features (and maybe supporting roles as well). So if water is just a stabilized version of oxygen, and the hydrogen bonds cause the molecules to behave in certain ways, then it seems almost as though I could understand water as oxygen with some extra hydrogen smeared around it. I am wondering in general about the role of hydrogen, since it seems like really just extra protons/electrons that pad molecules. Oxygen actually seems similar in its effects with oxidizing metals, although I don't really understand much about the chemical properties of oxidized things generally. Still, it seems like oxidation generally increases anti-conductivity and causes loss of ductility/malleability, which I have come to associate as the defining properties of metals due to their electron-abundance. So as I start to understand metal atoms as being little balls of electron-abundance, it makes me want to look at chemical reactivity as mitigation of that abundance and the various behaviors of the metals. Is this view too metal-centric and in reality matter is much more dynamic than variations of metallic (and non-metallic) behavior?

[mississippichem]

Oxygen actually seems similar in its effects with oxidizing metals, although I don't really understand much about the chemical properties of oxidized things generally.

 

Alright let me help you understand oxidation:

 

Oxidation is defined as the loss of electrons, reduction is the opposite and is the gain of electrons. Yes, you can have oxidation without oxygen, this is a terminology inconvenience. Usually, adding oxygen to a molecule ends up oxidizing that molecule though.

 

Every time a molecule oxidizes another molecule, it becomes reduced by the molecule it oxidized. So if A oxidizes B, then you can say that B has reduced A. Most of the time, elemental [plain atoms] metals tend to reduce non-metals. So lets look at an example with sodium, a very strong reducing agent.

 

[ce] 2Na + 2H_{2}O -> 2NaOH + H_{2} [/ce]

 

This is the full reaction equation for elemental sodium reacting with water [i chose this because it an easily analyzed and fundamentally 2 electron process. Multi-electron processes can get complicated]. So here, sodium metal is oxidized by water, and water is reduced by sodium metal. Let's break these into "half-reactions" for clarity.

 

*([ce] e^{-} [/ce]stands for an electron)

 

For the oxidation:

[ce] 2Na^{0} -> 2Na^{+} + 2e^{-} [/ce]

 

For the reduction:

[ce] 2H_{2}O + 2e^{-} -> 2OH^{-} + H_2 [/ce]

 

So now we can see how sodium is losing an electron, while water is gaining one. You can recombine these two half reactions to regain your original equation.

 

Still, it seems like oxidation generally increases anti-conductivity and causes loss of ductility/malleability, which I have come to associate as the defining properties of metals due to their electron-abundance.

 

Don't think of metals as having an electron abundance, think of them as being willing givers of electrons. In a bulk material, any given metal atom is actually electron deficient. All the metal atoms in the bulk share electrons in what's called a conduction band. Metals are metals because their effective nuclear charge, [math] Z^{*} [/math] (nuclear charge once you subtract out all the inner electron shielding) on the outer electrons is low; yielding a very low ionization energy. Thermodynamically speaking, it requires little energy to remove a mole of electrons from a mole of metal atoms, when compared to non-metals.

[lemur]

Alright let me help you understand oxidation:

Don't think of metals as having an electron abundance, think of them as being willing givers of electrons. In a bulk material, any given metal atom is actually electron deficient. All the metal atoms in the bulk share electrons in what's called a conduction band. Metals are metals because their effective nuclear charge, [math] Z^{*} [/math] (nuclear charge once you subtract out all the inner electron shielding) on the outer electrons is low; yielding a very low ionization energy. Thermodynamically speaking, it requires little energy to remove a mole of electrons from a mole of metal atoms, when compared to non-metals.

Good post. Clear example. What you're saying about metals and their outer electrons having low ionization energy and that forming a conduction band is basically the reason I started thinking that metals have "electron abundance" in the first place. In my mind, it's like atoms are onions and metals are onions with a lot of loose peel on the outside that can easily vibrate and transmit energy (ok, loose onion peels probably wouldn't be a good means of conducting waves of energy but if they were, say, those balls covered with flexible fingers sticking off them, they would). Anyway, the fact that the metals also easily give away electrons makes me think that is related to their ductility/malleability because it's like any practically any amount of energy displaces some electrons resulting in a type of surface tension among the atoms. Another way of looking at it would be that the more flexible outer electrons behave like a fluid between the atoms, which gets squeezed out, leaving a relative electron vacuum behind that causes the atoms to "suck up" to each other, almost like magnetic shavings clinging together in a lump.

 

Thanks for explaining that oxidation doesn't necessarily involve oxygen the element itself. I guess what it means is that however metals end up losing their "electron abundance" (sorry to keep using my pet term - I haven't yet figured out which of the other terms I should use instead) - that causes them to be more "electron dry," by which I mean that those flexible outer electrons that easily change levels and break away are no longer available for conduction, ionization, etc. Am I overgeneralizing - does oxidation not always have this effect?

 

Now what I don't get is why the opposite of oxidation is called "reduction."

 

 

[mississippichem]

Now what I don't get is why the opposite of oxidation is called "reduction."

 

If you gain an electron, your charge is "reduced" to a more negative value.

[Horza2002]

As Mississippichem has said, oxidation is an unforuntate terminolgy. It is used, however, because when the process was discovered, all the known processes involved oxygen. The first studies were metal oxides.

 

Examples of oxidation/reduction (aka redox) reactions that don't involve oxygen and metal-metal reactions. Some metal ions are capable of reducing/oxidising other metal ions. This depends on the oxidation potential of the individual metal ions and also the spin state of that ion.

Edited May 3, 2011 by Horza2002