Dear Science,
This question may seem a tad obscure, but it comes up when I wonder if I could have a molecule of water in my body that once passed through, say, Benjamin Franklin, or another famous (or infamous, for that matter) person.
How long do water and other covalently bonded molecules actually remain intact, i.e., with their original hydrogen and oxygen atoms? Are they promiscuous? Do they exchange atoms with other molecules frequently? How could one determine the age or stability of a given molecule?
Musing Over Beer In Ballard
I have sad news, my dear beer drinker in Ballard: There is virtually no chance that a water molecule that passed the lips of Benjamin Franklin (Science’s favored founding father, by the way) has passed through your lips. Covalent bonds seem like they should be so solid and enduring, yet they are fleeting—especially in the case of water.
Atoms, in contrast, are generally enduring. Aside from the more vigorously radioactive of elements, atoms retain their identity for eons. That’s not to say atoms are universally happy with existence.
Let’s think back to high-school chemistry. Atoms are made up of nuclei (composed of protons and neutrons) surrounded by shells of electrons. All atoms wish to have their outermost shell of electrons filled. For helium and hydrogen, the outer shell can hold two electrons. Hydrogen, with a single electron, is only halfway there. All other atoms—including oxygen—need eight electrons to have a full outer shell. (This is why the periodic table has eight columns.) Oxygen has only six electrons in the outer shell, needing two more to fill it out. The covalent bond in water is the grand deal between oxygen and hydrogen atoms: By sharing their electrons, two hydrogen atoms and one oxygen atom can convince themselves they are complete—like their smug cousins helium and neon.
With surprising speed, this arrangement breaks down and re-creates itself. The oxygen atom in a water molecule is chock full of electrons (three pairs, oh my!) begging for a hydrogen ion (a lonely bare proton) to jump from another water molecule and nestle into a sweet pair just waiting. The result of this shifting is a hydronium molecule (three hydrogens and an oxygen) and a hydroxyl molecule (an oxygen and a single hydrogen). This shuffling about occurs in all water, more so when things warm up a bit. With all of this, a given water molecule lives for only about 10 hours.
So it ends up being highly unlikely that a single water molecule—a pair of hydrogens and an oxygen—would remain attached across the centuries. Blame equilibrium, my friend, and the deliciously low disassociation constant of water.
Associatingly Yours,
Science
Send your science questions to dearscience@thestranger.com.
ZZzzzzz
Hot, young Hydrogen-Oxygen pair looking for willing additional Hydrogen. Must be into nesting and covalent bondage. Please send photo of your electrons.
wow! 10 hours is a LOT longer than I would have expected.
I am not being sarcastic. Without looking anything up I would have guessed on the order of seconds…
Another fabulous Science!
“All other atoms—including oxygen—need eight electrons to have a full outer shell. (This is why the periodic table has eight columns.)”
Not true – the periodic table has 1 column in period 1, 8 columns in periods 2 & 3, 18 columns in periods 4 & 5, 32 columns in per 5 & 6.
8-electron “fullness” only applies to the s and p orbitals. There’s d and f orbitals to fill too, in order to reach “full electron shells”.
“All other atoms—including oxygen—need eight electrons to have a full outer shell. (This is why the periodic table has eight columns.)”
You’re forgetting that the periodic table has 2 columns in period 1, 8 columns in periods 2 & 3, 18 columns in periods 4 & 5, 32 columns in per 5 & 6.
8-electron “fullness” only applies to 2s+2p orbitals (2+6), of which oxygen is NOT full at 8 because of the 2 electrons in the 1s orbital. – oxygen is 1s(2) 2s(2) 2p(4), which means the 2p is not filled. Not to mention that there’s d and f orbitals…
“the periodic table has eight columns” … sheesh. Where did you take high school chemistry? You should give your diploma back.
I’m a curious novice, so I looked into this a little, and found this article:
http://www.lsbu.ac.uk/water/ionis.html
That does talk about something happening once every 11 hours for a given molecule (25C), but that sounds like rate of the reaction 2 H2O <–> H3O+ + OH-, whereas the Grotthuss mechanism would also cause the molecules to rearrange themselves but at a far higher rate. In the Grotthuss mechanism, the protons bump each other off in a way that sounds similar to how electrons flow in electric current.
But the oxygen atom involved in the water molecule was almost certainly at one time pissed out by a dinosaur.
OK, so since we’re all geeking out here…what gives an atom its identity? Just its nucleus? Or could it be in some combination of its nucleus and its electrons? If you take two atoms and swap some of the electrons, do the two original atoms maintain their identity, or do you have two entirely new hybrid atoms? Because if it’s the latter, atoms preserve their identity for only a matter of a picosecond, if that. I think we can all agree that if Golub and I had a dual kidney transplant, where they put one of mine in him and put one of his in me, there’d be no indentity confusion afterwards. That’s because we think of our souls as dwelling in our brains, not our kidneys. But here’s a little known true fact, true both scientitically and theologically: the soul of atom is embodied in its electron cloud, and not in its inert, lifeless nucleus.
Eric – Even if you had a single hydrogen atom sitting there in a vacuum, it would not keep its electron for very long. All the time in the vacuum around and inside atoms, there are electron and positrons spontaneously appearing and annihilating with each other. Every now and then, such a positron will annihilate your electron, and the other spontaneously created electron will takes its place. I’m not sure, but I think that is happening constantly, such that each electron is really a cloud virtual particles annihilating each other, with one net particle always remaining. When physicists talk about canceling out the infinities in their equations, they are basically taking account of those clouds.
The same thing is going on with the quarks inside the proton of the hydrogen atom.
Oh goodness. What makes an atom an atom or “gives it it’s identity” is the number of protons it has. All atoms with 2 protons are helium, all atoms with 6 protons are carbons. The number of neutrons can change, and that ain’t no thang but yielding different isotopes. The number of electrons has no bearing on whether or not a carbon atom is a carbon atom or an iron atom an iron atom. True the electron cloud is where all the action (chemical reactivity) happens, but the soul of the atom would be in it’s nucleus because it is therein that resides what makes it what it is.
BTW, in my opinion, whoever does Dear Science sucks. I haven’t seen a question and answer column that doesn’t contain at least 1 or 2 major errors.
@11: You can have many different atoms with two protons that are wildly different from one another. For instance, take two proton, two neutrons, and two electons, and you’ve got a garden variety neutral helium atom. Take two protons, two neutrons, and zero electrons, and you’ve got a doubly charged helium ion, a radically different object, from a chemical point of view, even if both objects have the word “helium” in it. It’s a theologocal question to be sure, but to the extent each atom has its own unique immortal soul, I’m quite sure it does not reside in the human-assigned word, “helium”.
Now, if you had an atom with two protons, three neutrons, and two electrons, it would be chemically smilar to the first example, and it would still bear the name, “helium”, but it would be radioactive! Different now along a very different axis. I’m aware this final example undercuts the point I made @9….
As for you assertion that “Dear Science” sucks, I completely disagree. I think it’s consistently interesting and only very occasionally wrong. Golub’s trying to write a column that apeals to a wide audience. Hard to write a column that interests the general Stranger reader but doesn’t rile the pedant like myself, or the true savant, like 8chto@10.
Inaccurately describing something, giving wrong, misleading or false information is something that a supposed science ‘expert’ should try their hardest to never do. The common non-science lay person relies upon scientists for their scientific knowledge and giving false information or inaccurate information for the sake of simplicity is morally offensive.
Radioactive Helium is no different than non-radioactive helium other than the fact that it is radioactive. Helium is helium is helium. All the reactivity comes from electrons, but doesn’t change what type of atom it is, only it’s reactivity.
OK, so suppose there were these two people named Siz, Siz Jones and Siz Smith. Siz Jones was interested in understanding the chemical and physical properties of atoms. Siz Smith was interested in not making “morally offensive” mistakes in reciting the names of atoms. Would you say then that these two Sizs, these two people who could hardly have a more different approach to science, were basically the same “type” of person, because “A Siz is a Siz is a Siz?”
Or (and this is what I’m hoping is the case) is it actually that you, Siz, have a teeny bit of a proton fetish? It’s entirely cool if you do. I see you’ve recently joined the community of Stranger/SLOG commenters, but if you’ve been lurking for a while you’ll know that there are all types here (Get Golub drunk, then get him talking about Golgi organelles!) and all are welcome, as are you! If there’s one informal rule, it would only be, “own your kink.”
Well Eric from Boulder, this Siz has about 14 years of training in the physical sciences and could answer simple science questions clearly AND accurately without giving the public false or inaccurate information.
Don’t confuse chemical identity with reactivity. You see, dicationic helium basically doesn’t exist. Dicationic Cesium, however, does exist. Because Cesium and Helium have different numbers of protons they have completely different properties. Dicationic Cesium and metallic cesium also have different properties but, they are both still cesium, which reliant upon the electronic state have completely reproducible and reliable reactivities.
I would never be so bold about something that was absolutely and 100% wrong to bold it. Of course we can always ignore the transition metals, lanthanides and actinides. And then yes, the periodic table does have 8 columns. As a scientist I do find it morally reprehensible when other “scientists” relay wrong or inaccurate information. If one can not explain a scientific concept in lay person’s terms without giving inaccurate or false information, they shouldn’t do it.
14 years of training? Get. Out.
You {i are} an oldtimer!
Some grad students around Boulder have come close to tying your record, but they don’t often brag about it.
But seriously, Siz, I think you’re mistaken if you think it’s all that easy to be understandable and 100% accurate, especially if you throw in the requirement that you be at least a little bit interesting, also. If you are really that good at it, you could start your own blog!
Someone with as much science training as you have will know that at the beginning of a scientist’s training, courses tend to emphasize simplified models of our current understanding, and, as the years go by, they add in more and more details, more and more realism. The instructors who gave you those earliest lessons, now 13.5 long years ago, didn’t try to tell you everything they knew all at once, but simplified things. Do you look back at your early teachers in anger for their having behaved immorally?
You and others in this thread have taken Golub to task for his comment about the eight-column periodic table. Golub’s an MD. Come on. He knows what they look like. But you can go a long ways towards understanding what’s going on if you start with just the eight columns — indeed that’s how many there were when the idea of the table was first introduced (I expect you learned that fact, sometime in the last 14 years.) It’s easier if you don’t get all bogged down in d- and f-shell minutiae. For biochemistry all the way up through, I dont know, maybe hemoglobin, eight columns is plenty.
As for your always being 100% accuurate yourself, I could make a case that your statement “dicationic helium essentially doesn’t exist” is itself way wrong. Here in our solar system, there is in fact vastly more abundance of doubly ionized helium than of neutral helium. OK, so maybe you could say, “hey, I wasn’t including helium in the sun!” And sure, being geeks, we could have big fun jousting over that point. If the discussion got a little heated, I might call you “disingenuous” or, heck, even “dim-witted.” But I wouldn’t call you immoral. Lighten up, friend!
Ah ha! That’s why I said basically. Duh.
Well, colleague, it’s been real, but there’s probably no one out there in all of internetland interested in this thread except for the two of us and even I’m fading. If I can sum up the moral situation as you have laid it out: the reason Golub’s post is morally offensive and yours isn’t is that you included the adverb “basically”, and he didn’t. Yes? A lot hinges on a word!
I agree there are errors from time to time in this column, but I totally disagree that “giving false information or inaccurate information for the sake of simplicity is morally offensive”. For example; people once thought the earth was flat, then the view changed to that of a sphere. Both are technically wrong, the earth is an oblate spheroid (which itself is not totally accurate (consider mountains, valleys, houses). I contend that saying the earth is a sphere is less wrong than saying it is flat.
Trying to educate a woefully unscientific American general population is something we all need to do, even at the risk of slight errors. I applaud “Dear Science” for helping educate and for the amount of effort that goes into getting it publishable.
Instead of nitpicking on this blog, I encourage all here to do their some small scientific outreach.
I do my part by doing more than some small scientific outreach. I go out into the community monthly and work with 7 and 8 year old children to teach them about chemistry. Man, do they get excited.
today’s’ facts are tomorrow’s fallacies.
I have a related question: how easy is it for more water to get made out of hydrogen and oxygen gases in the atmosphere? Does it happen much naturally? In other words, when water is dispersed into H and O2, is it gone forever or do we regain some of it through natural processes?
My question is this: how long do twinkie molecules stay bound together? I mean – if I were to leave one in the back of a cupboard for, say, 100,000 years would the cream still be cream?
Yours patiently, Simples.