The Loneliest Proton

No matter how hard you try you will never be able to grasp just how tiny, how spatially unassuming, is a proton. It is just way too small. A proton is an infinitesimal part of an atom, which is itself of course an insubstantial thing. Protons are so small that a little dib of ink like the dot on this “i” can hold something in the region of 500,000,000,000 of them, or rather more than the number of seconds it takes to make half a million years. So protons are exceedingly microscopic, to say the very least.  ~ Bill Bryson

That excerpt was blogged by Althouse without much further comment. The reader is supposed to recall from high school or college chemistry just how small the proton really is -- it is after all just a nuclear particle.

Protons cluster in every atom except for hydrogen where they appear alone.  In humans, protons mostly nucleate in groups of eight (as found in oxygen) or six (as found in carbon) with attendant neutrons, but they also go it alone in hydrogen.

Despite the proton's exceedingly tiny size in hydrogen, it is readily detected when placed in a magnetic field. They can even be spatially located in soft tissue by MRI. So there's a nice trade off. If only all the  smallest and hardest to see elements were so easy to detect.

Hydrogen is also giving us a glimpse into the mind as in MRI imaging of the brain.

Exceeding Nature

Original

The scheme belongs to a recent chemistry paper entitled "Nonmetal Catalyzed Hydrogenation Of Carbonyl Compounds" which I think shows significant advancement in chemistry. For the non-chemist, I'll unpack the title.

You may not be interested in hydrogenation, but hydrogenation is interested in you: it feeds you. The metal-catalyzed hydrogenation of vegetable oils is big business. You may have gotten away from trans-fats, but are you free of cis-fats?  How about saturated fats? The food industry uses hydrogen and metals like nickel to hydrogenate food stuffs. And then there is the "hydrogenation" of nitrogen to make fertilizer.

What these guys in London did is remarkable because they used hydrogen (H₂) to make alcohols (top right) from ketones (top left). And they used only C, H, O, B, and F atoms, spatially arranged as shown. No metals.

Nature has little use for H₂, the simplest of molecules. Relatively little free H₂ exists on earth. There is a class of enzymes called hydrogenases, but guess what? They use metals to activate H₂. So this work goes above and beyond Nature itself.

Radiant Transfer

Photo taken tonight at the Oceanside Harbor beach at sunset:

OK, it's not the best quality, but it has all the classical elements: earth, wind, fire, and water.

The juxtaposition of the campfire and the sun reminded me of a conversation I had with my kids two years ago: link

Me:   Did you see that?  Where does that energy come from?

Son:   Hydrogen?

Me:    You think there's hydrogen inside the log?

Son:    No

Me:    What's in the log that burns?

Son:    Wood

Me:     Where does the wood come from?

Son:    The tree makes it

Me:     Where does the tree get energy?

Daughter:  From the sun!

Me:     Yes!

Son:     But isn't the sun hydrogen?

Neither a Borrower Nor a Lender of Electrons Be

Neither a borrower nor a lender be;
For loan oft loses both itself and friend,
And borrowing dulls the edge of husbandry.
This above all: to thine own self be true,
And it must follow, as the night the day,
Thou canst not then be false to any man.

~Act I, Scene 3 of William Shakespeare's Hamlet

Polonius was speaking of money or gold, giving advice to his own son Laertes. But what sort of miserable person never borrows nor lends money?  A King? Nobility?

The noble gas helium neither borrows nor lends electrons. The price it pays is lonely chemical stability. Helium is the most noble of the noble gases, grudgingly condensing to liquid only at extremely low temperatures.

Hydrogen is the the most common element in the universe and it freely gives, takes, and shares electrons with others. It is the most promiscuous element, forming compounds with practically all other elements except the noble gases.

Those very first two elements display the full range of chemical reactivity and stability--another reason why they sit atop the Periodic Table at opposite ends, bracketing the whole thing as it were. And it's all done with the simplest spherical orbital -- the lowly 1s orbital. Every other heavier element has those same electrons at their very core too. But they aren't part of chemistry -- they're just there -- an inert core. And they're not mere abstractions either--they're part of me as well.

Flogging Phlogiston

Oxygen burned two great ideas in chemistry. Not literally, but understanding oxygen and oxidation undid two great ideas. One was called Valence Bond theory and I considered its undoing back here. VB theory is still useful and is taught in middle and high school chemistry curricula. The other great idea was called Phlogiston theory. Of course the Chinese had their own take on oxygen which you can read about here: link

The word "phlogiston" came from the ancient Greek word φλογιστόν ("burning up") and was promulgated by German scientists beginning in the 17th century. The notion had probably been around much longer because the idea was a very intuitive one. Phlogiston theory taught the existence of an element called phlogiston, a substance without color, odor, taste, or mass. Phlogiston was liberated when something burned or slowly rusted. Think of what you feel in front of an open flame. Not really so far-fetched, the notion was close to our modern notion of energy consumption, in so far as we suppose substances like fuels have "energy content." We speak of hydrocarbon's energy content in BTUs as if it were something we could distill and put in a bottle.

Phlogiston was a German notion and was undone by men like Antoine Lavoisier who showed that metals increased their mass when they burn or rust, inconsistent with something being lost or given up. Unfortunately, Lavoisier lost his head in the French Revolution for his royalist sympathies.  A dead cat bounce for Phlogiston occurred around the turn of the 19th century, just after water electrolysis was discovered.


Alessandro Volta's Pile 

When William Nicholson and Anthony Carlisle inserted the two wires from their voltaic pile together into a vessel of water, they also galvanized the entire scientific world, creating a sensation as great as any scientific discovery ever made. In Nicholson's words:

It was with no little surprise that we found the hydrogen extricated at the contact with one wire, while the oxigen [sic] fixed itself in combination with the other wire at a distance of almost two inches.

What actually happened depended on the type of metal wire used: when they used copper, hydrogen gas evolved at one wire while the other wire became "fixed with oxygen" meaning it turned to copper oxide (greenish blue). But with platinum or gold wires, hydrogen gas evolved cleanly at one wire while oxygen gas evolved cleanly at the other electrode. The great puzzle was not that the two different gases were produced, but rather that they were produced at different electrodes. It seemed to everyone that if the gases both came from the decomposition of water they should both appear at the same place.

Now the notion that hydrogen and oxygen were distinct elements was not universally accepted. It was not settled science. One of the doubters was a German named Johann Ritter. Ritter was no slouch.*  He repeated the Nicholson and Carlisle experiments and concluded that it was impossible for the gases to be produced from the decomposition of water since there was no way that a gas could travel through one wire, through the pile, and out through the other wire. The truth, Ritter argued, was that:

Water is an element

In Ritter's view, "oxygen" was just water plus positive electricity and "hydrogen" was just water plus negative electricity. He nearly set science back 2000 years. That water was an element and electricity was like phlogiston was ancient thinking. Great minds, including Michael Faraday, puzzled over water electrolysis for years. Bear in mind that in the early 1800's nobody had yet thought that water could ionize into H⁺ and OH^-. The proton (and the electron) had not yet been discovered. But the Germans ultimately lost the argument.

We now understand that water is consumed at both electrodes and electrons flow into one electrode and out the other:

At one electrode we have:  2H₂O   +   2e^-   ---->    H₂(g)   +    2OH^-
At the other electrode:        2H₂O    -   4e^-   ---->    O₂(g)   +    4H⁺  

I remember this stuff by recalling the origin of the word "oxygen" which means "acid-forming." The electrode which forms oxygen also forms acid. Of course the H⁺ and the OH^- swam the two inches back towards each other in Nicholson's experiment and remade neutral water, and completed the circuit.
_________________________

*Ritter was no slouch:

"William Herschel discovered infrared radiation because thermometers, which had recently been developed in Europe, showed a higher temperature just beyond the red end of the visible spectrum of sunlight. The German chemist Johann Wilhelm Ritter (1776-1810), after hearing about Herschel’s discovery from 1800, identified another “invisible” radiation which we now know as ultraviolet (UV) in 1801. He experimented with silver chloride since blue light was known to cause a greater reaction to it than did red light, and he found that the area just beyond the violet end of the visible spectrum showed the most intense reaction of all." reference

The Basics Of How Chemistry Is Like Sex

Anyone who has cleaned with Windex has whiffed ammonia, a substance with a rich and interesting history that includes its very name: link.  Note that ammonia was once called animal alkali. Muslims-in-science scholars should take note of the origin of the word alkali, but should take care not to get the concept of alkaline bases etymologically confused with that other Arabic word meaning base.

Ammonia gas easily condenses into a liquid when compressed (Albert Einstein and his erstwhile student Leó Szilárd once patented a refrigerator with no moving parts that used ammonia instead of freon). If Szilárd's idea had gone anywhere, he may not have bothered to have conceived the atomic bomb.

Ammonia has been variously depicted as NH₃ or better as :NH₃ or better still with its electron "lone pair" on full display, as:

The lobe-like appendage sticking up is called a "lone pair" because there are two electrons in the orbital and because they're not associated with any atom except nitrogen.  Some depictions of ammonia omit the lone pair but here I prefer the "fig leaf is off" depiction.

Ammonia is perpetually in search of an acid to quench its baser instincts. Given a proton like H⁺, ammonia and the proton instantly couple to make ammonium NH₄⁺ in which all four H's become equivalent. In a real sense, the incoming acid polarizes the other three H's, sucking electrons away from them, making them all more acidic.

Acerbic Wet

The Danes and the Brits pioneered graphic depictions of simple chemical reactivity. Brønsted and Lowry independently shocked early 20th century chemists with their notions of spontaneous self-ionization of water:

Brønsted-Lowry theory explains how even the purest distilled water conducts electricity (which requires something charged). In their scheme, one water acts like a base by accepting a proton, while the other one acts like an acid, donating a proton. The slight but measurable extent of such H-swapping is real enough--a normal glass of water has a measurable concentration of H₃O⁺ of about 10^-7 units or a pH of 7 (pH is like a Richter scale). An equal & countervailing amount of hydroxide, OH^- neutralizes the acid.

Now consider adding anything to that glass of water which increases the amount of H₃O⁺ (but not OH^-).  Such a thing which donates an H⁺ to a neutral water molecule is called an acid in English.  The Germans call them Säure, which is related to our word sour. Svante Arrhenius (the august savant who also thought up AGW), came up with the idea first.

Lesson Learned

(Adapted from conversation around the campfire last night). As we're all staring into the fire, suddenly a part of the log flares up:

Me:   Did you see that?  Where does that energy come from?

Son:   Hydrogen?

Me:    You think there's hydrogen inside the log?

Son:    No

Me:    What's in the log that burns?

Son:    Wood

Me:     Where does the wood come from?

Son:    The tree makes it

Me:     Where does the tree get energy?

Daughter:  From the sun!

Me:     Yes!

Son:     But isn't the sun hydrogen?

Hydrocarbons: Still Our Old Friend

As I write this we're all still watching the horrible oil rig disaster unfold. Here are some spectacular photos of the event via Twitter.

Eleven dead already.  The entire Gulf of Mexico coastline threatened. Is there already talk of this catalyzing a move further away from oil? The fact is that oil and related hydrocarbons are still relatively cheap and plentiful. Or is the whole enterprise just too big to fail?  I worked for a time on a project devoted to making gasoline from natural gas. During this time I became familiar with the business phrase "shutdown economics" which in that case meant that any new technology had to be good enough to make the existing technology unprofitable and pay for the cost of recapitalization.

We'd all like for wind and solar energy to be cheaper. But we're not anywhere close to replacing hydrocarbons.

H Is For Humble Hydrogen

The sun consumes about a half billion tons of hydrogen every second, fusing mass into helium and radiating the excess as energy. We just sit back on sunny days and bask in the afterglow of the nuclear holocaust at a very safe distance, thinking nothing of it. Our nonchalance towards any solar dimming is justified by considering that the sun should last another 5 billion years or so.

Hydrogen fuel cells (chemical, not nuclear) are already used in spacecraft, and modern rocket engines burn liquid hydrogen and liquid oxygen. But back on earth, there is talk of using hydrogen as an energy source to replace hydrocarbon fuels. Hydrogen gas burns cleanly, as the very name reminds us: hydrogen = water generating; the catch is that hydrogen gas has to be made because little is found naturally on earth.

By far the cheapest way to make hydrogen gas is from natural gas, CH₄, using a process that co-produces CO₂ (the carbon atom has to go somewhere). But another little appreciated fact is that a big consumer of hydrogen gas is the fertilizer industry—hydrogen is used to make ammonia from nitrogen—and another big user is the food industry—it is used it to hydrogenate vegetable oils. Any large-scale diversion of existing hydrogen to transportation fuels will ultimately raise the price of food via the costs of ammonia fertilizer and food processing costs. Sound familiar?

What’s really needed is a new and different way to cheaply make hydrogen gas—something like the efficient photolysis of water or the electrolysis of water using electricity from nuclear power plants. Both technologies exist, but they are economic nonstarters. For my money, I’d rather see cars run on methane, rather than going through the additional process hoops of converting the methane to hydrogen gas. A similar argument holds for bio-fuels, which I will discuss when I get to carbon and oxygen.

Hydrogen is the most promiscuous chemical element, pair bonding with nearly every element and even forming special bonding threesomes called hydrogen bonds. Hydrogen bonds are the principle force binding the two strands of DNA together. Arguably, hydrogen bonds are present at the conception of human life: when the two single strands of DNA, one from the mother, one from the father, join for the first time, those strands are united by about 3 billion hydrogen bonds. Each one is worth a small amount, but together, summed over the entire double helix, amounts to a formidable binding glue.

The themes of family and weak and strong chemical forces reminds me of some lines from the David Lynch movie “The Straight Story." Richard Farnsworth says (while demonstrating with sticks):

When my kids were young I played a game with them. I'd give each of them a stick. One for each of 'em, and I'd tell them to break it. They'd do that easy. Then I'd tell them to make one bundle of all the sticks and try to break that. And course they couldn't. I used to say that was family, that bundle.