Another Quantum of Solstice...

Rutherford and Bohr

[this story continues in part from here.]

Ernest Rutherford discovered the atom's very kernel, the nucleus, but his tiny solar system model of the atom failed. It failed because it had a fatal flaw according to classical electromagnetic theory: Viewed side-on in the plane of the ecliptic, the orbiting electron oscillates charge from side to side and should behave like a miniature transmitter, broadcasting electromagnetic energy like a Marconi transmitter. Giving off energy, bit-by-bit, the electron should spiral into the nucleus. Rutherford never explained that away.

The Importance of Being Near Ernest

Luckily, Rutherford confided his 1909 experiments to young Niels Bohr prior to publishing them. Rutherford had invited Bohr to Manchester to study physics after a brief (and apparently unsuccessful) stint at Cambridge. Inspired,* Bohr spent the summer of 1910 and the subsequent spring (taking time off to marry and to honeymoon), devising his own theory which he published in 1913 (two years after Rutherford finally published his planetary model in 1911).

Bohr got around Rutherford's electron death spiral problem by postulating that it didn't happen! That may sound audacious and even glib, but he overcame "illogical leaps" by solving a bigger mystery which had puzzled generations of scientists: he explained the long-known but little-understood signature hydrogen lines observed in the spectra of stars (recall that stars are mostly hydrogen). According to Bohr, the lines represented quantum leaps in units of energy. He did the math for the hydrogen atom to prove it. The simplistic hope that atoms and the universe were fundamentally similar -- the too small to be seen and the too big to be noticed were whirling masses in motion or "turtles all the way down" -- shone briefly.

According to Bohr's new 1913 theory, electrons encircled a nucleus, but only in stable, fixed-distance orbits (shades of Bode's earlier but discredited planetary law?) but without the continuous death spiral energy radiation. Bohr called his quantized orbits "stationary orbits" (whence my title). A quantum of solstice or standing still.

Electrons in Bohr's stationary orbits still gained or lost energy -- but only by jumping from one orbit to a bigger orbit and vice verse. That was revolutionary. Bohr's math worked out too and depended on Planck's constant which was only 13 years old then.

Planck quantized radiation and Bohr quantized matter--viz, electrons. Scientists struggled in subsequent years with the question of whether electrons were waves or particles and whether light rays were waves or particles. They worried about the meanings of such apparent dichotomies until they gradually realized that they were fighting about language and not about science.
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*Inspired is an understatement

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My inspiration for the "Quantum of Solstice" is here at Victoria's old blog, to whom I dedicate this blog post.

The Proof Was In The Pudding

[continued in part from here]

After Thomson discovered and defined the negative portion of the atom, his attention turned to the positive portion which was ill-defined. One problem was that there was no simple tool to probe inside atoms. Electrons could be fired at matter, but so what?  They just softly scattered off (it turns out that organized matter diffracts them but that came later).

The alpha particle was Rutherford's baby: he had named it and had shown that is was a helium atom stripped of electrons, i.e., He²⁺.  By 1909, Rutherford and his students were firing alpha particles at everything in sight, looking for any new and unusual effects, but also testing theories about the positive part of Thomson's Plum Pudding Model.

Rutherford had earlier noted the thickness of sheets of materials needed to stop alpha particles. But why did they? There was nothing about JJ Thomson's atom that should get in the way. If the positively charged portion of each atom were a uniformly thin gruel, alpha particles should sail right through.  But they noticed deflection--eppur si muove.

Eventually, they began measuring how much thin sheets of gold foil deflected beams of alpha particles. The experimental set-up involved aiming a beam of alpha particles at a gold foil and putting a detector on the other side to measure deflection angles of the "filtered" particles. In a sense, Rutherford was trying to quantify the density of the positive pudding portion. The more closely they looked, the more deflection they observed. Almost as an aside, Rutherford suggested putting the detector in front of the gold foil. When they did so, and to everyone's utter surprise, a detectable amount of alpha particles appeared to bounce off the gold foil rather than pass through it. It took Rutherford two years to digest, confirm, reconfirm and then to announce what this all meant. In Rutherford's words:

It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus. It was then that I had the idea of an atom with a minute massive center, carrying a charge.

[Continued in part here]

The First Quantum Mechanic

Max Planck was the first quantum mechanic.  He began as an "old school" mechanic, thoroughly steeped in Newtonian mechanics and Maxwell's electrodynamics; those laws conveniently sorted physics into the "corpuscular" and the "ethereal" domains, a dichotomy that corresponded to things having mass and things lacking mass, i.e., radiant light. Higgs had something to say about this later.

Isaac Newton had solved the age-old riddle of why apples fall, allowing astronomers to predict the motions of the heavens. Miracle, mystery and authority. Newton also dabbled in light, describing reflection and interference--along with his famous prism experiments--but the mathematical laws governing light propagating "through the ether" were first described by a Scotsman, James Clerk Maxwell. Newton's Laws of Gravitation governed masses while Maxwell's electrodynamics ruled the waves. Planck came along in 1900 and sort of melded the two theories at their interface.

Physics then had a big unsolved problem called "black body radiation." Heating kilns and ovens made the inside walls glow--first red, then yellow, and finally white hot. Glass makers and potters could even gauge an oven's temperature based on its color inside. Adding more heat to an oven made the walls give off progressively higher energy light but there was a limit: ovens would not begin to emit UV light. Light bulbs were another 19th century invention that used heat (electrical resistance) to produce light and Planck was motivated in part by practical concerns.

What Planck did can be summarized visually with a plot of light intensity versus wavelength:

Planck's theoretical curves (berechnet) agreed beautifully with experiment (beobachtet). Note that there are seven different non-overlapping curves corresponding to progressively higher temperatures. Prior attempts to predict the same phenomenon, based on classical electrodynamics, had failed. These attempts are neatly summarized in this graphic:

The green line corresponds to Planck's law and to reality; the red line, Rayleigh-Jeans Law, only worked at low frequencies (long wavelengths), while the blue line, Wien's Law, worked only at the high frequencies (short wavelengths).  As an aside, the red line's straight up ascent was later referred to as the "Ultraviolet Catastrophe" as a sort of metaphor for the failure of classical theory to account for the reality of Planck's Law. But Planck did more than meld two theories--he invented anew.

The newer science of thermodynamics and Maxwell Boltzmann in particular had shown that tiny invisible yet indivisible atoms could statistically sum to bulk properties. The details are grounded in probabilities rather than certainties, much like my Parable Of The Gas. What Planck did was to apply Boltzmann-like statistical mechanics to the problem of black body radiation.

Planck viewed a red-hot oven (black body radiator) as material in equilibrium with light--sort of a transubstantiation of the ethereal and corpuscular. He named the nexus--the unseen--"resonators" and counted them in a statistical way, describing their behavior mathematically. This was all well before anyone knew or even thought that atoms were held together by electrons--atoms were still thought to be amorphous blobs. That something as seemingly seamless as light should be treated like discrete masses when it interacted with matter was an assumption but it proved key to deriving the solution to the black body problem. There was no other way to explain the behavior. What Planck did was revolutionary, but he did not do it because he understood why--he did it because his theory fit experiment. Werner Heisenberg later stated Planck's insight most succinctly and in most certain terms:

Radiant heat is not a continuous flow and indefinitely divisible. It must be defined as a discontinuous mass made up of units all of which are similar to one another. 

Around the time of Planck's insight, another, younger German physicist appeared on stage. He was then a Swiss patent examiner and barely known, preoccupied with developing his own theories of relativity, but his elastic mind intuitively wrapped around what even Planck had trouble fully accepting and generalizing.  Einstein took Planck's teachings and explained the photoelectric effect--why blue light but not red light could make certain metals conduct electricity. It seemed counter intuitive that even the most intense red light could not do what the faintest of blue light could do. Einstein explained that only blue light was energetic enough to knock electrons free. There were energy thresholds and band gaps at the atomic level. Discontinuities and E=hv.

According to Thomas Kuhn, Planck needed the goading of Einstein and Paul Ehrenfast afterwards to fully realize what he had done. Certainly Planck's older contemporaries were doubters too. In Planck's words:

A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

Planck and Einstein remained close friends throughout the 1930's. Planck, conservative Christian, and Einstein, agnostic Jew, enjoyed making music together when not discussing physics in Wilhelmine and Weimar Berlin--while it lasted (maybe they did discuss the physics of music--frequencies, harmonics, metered beats). Planck tried in vain to intervene on his friend's behalf during the rise of the Nazi regime but he ultimately failed.

There was even greater sadness for Planck besides the exile of his great friend Einstein; there was the trial of his eldest son Erwin at the hands of Roland Freisler, whom I described back here. The Nazis executed Erwin Planck just a few heartbreaking months before the whole regime finally collapsed. The older Planck never recovered from the loss of Erwin and died just two years later in 1947. Here they are during happier times:

Max and son Erwin Planck

Erwin Planck on trial for his life before the People's Court, arrested and charged as part of the July conspiracy to assassinate Hitler:

Erwin Planck vor dem Gesezt in 1945

Erwin Planck, like so many others, was only involved in aftermath planning--helping to draft a post-Hitler German Constitution--and not the actual assassination plot.

The elder Planck's life sort of tracked a shape: A half-century of slow triumph peaked in the 1930's and then precipitously declined, much like the shape of one of his triumphant black body radiation curves which conquered physics. Post-war Germany honored Planck by renaming the Kaiser-Wilhelm-Gesellschaft (its premier scientific society) the Max-Planck-Gesellschaft.

Rumford, Soddy, and The Crash

Frederick Soddy (1877-1956)

Despite years of formal education in chemistry, I'd never really heard of Frederick Soddy until I started reading about the early days of radioactivity. He wrote a book called The Interpretation Of Radium (1909) which is available free online here.  The book so influenced H.G. Wells that he dedicated his book, The World Set Free (1914), to Soddy.

Soddy seems to have had two careers--first as an accomplished physical scientist (Chemistry Nobel in 1921) and then as a sort of social scientist, but more accurately as a social activist during the Great Depression. In this way he was a prototype Linus Pauling, who won both a Chemistry Nobel and a Peace Nobel for his activism.

Soddy was a chemist by training but today he'd be called a radiochemist. He must have seen or heard firsthand many of the key discoveries in nuclear physics in the late 19th and early 20th century, first at Oxford and then as graduate student with Lord Rayleigh. Afterwards, Soddy moved to Canada around the same time Ernest Rutherford did and the two joined forces. Together they discovered the natural transmutation of elements. Soddy's Nobel Prize citation reads:

for his contributions to our knowledge of the chemistry of radioactive substances and his investigations into the origin and nature of isotopes.

His isotope work came later.

Recall that Count Rumford first paid attention to the heat given off boring cannon and thereby converted our notions of energy.  Like Rumford, Soddy first realized how much heat and energy radioactive decay gave off--orders of magnitude more energy than burning fossil fuels did and it was also seemingly inexhaustible. Soddy was so prescient regarding how much energy was locked inside uranium, radium, and thorium that he warned Britain's government about the dangers of "atomic" bombs during the First World War.

The notion of cheap and abundant atomic energy crested in 1954 with Lewis Strauss' famous too cheap to meter statement, though it appears that he was referring to hypothetical hydrogen fusion reactors.

Soddy died in 1956 in relative obscurity. This (from the Wiki bio) is intriguing:

In four books written from 1921 to 1934, Soddy carried on a 'quixotic campaign for a radical restructuring of global monetary relationships', offering a perspective on economics rooted in physics—the laws of thermodynamics, in particular—and was 'roundly dismissed as a crank'. While most of his proposals - 'to abandon the gold standard, let international exchange rates float, use federal surpluses and deficits as macroeconomic policy tools that could counter cyclical trends, and establish bureaus of economic statistics (including a consumer price index) in order to facilitate this effort' - are now conventional practice, his critique of fractional-reserve banking still 'remains outside the bounds of conventional wisdom'. Soddy wrote that financial debts grew exponentially at compound interest but the real economy was based on exhaustible stocks of fossil fuels. Energy obtained from the fossil fuels could not be used again. This criticism of economic growth is echoed by his intellectual heirs in the now emergent field of ecological economics.

Technical Difficulties

Technetium was discovered relatively late. Actually it wasn't discovered--it was made.  I suppose it was "discovered" that every isotope was radioactive and unstable. And even though some isotopes are relatively mild alpha and beta emitters (not gamma)--special handling precautions are required. So those are two good reasons why technetium chemistry is relatively unexplored. I'm curious about what's still unknown. Look where Tc sits in the Periodic Table: link It sits on the middle leftern edge of the noble metals, many of which are catalytically active. Even manganese lying above and rhenium lying below are catalysts--used mainly for hydrocarbon oxidations. I have some hunches about what technetium could do but I'm keeping them to myself for now.

I'm not saying that technetium's chemistry has been completely ignored--it hasn't. But generations of routine, curiosity-driven experiments have still not been done. Technetium has not been thoroughly interrogated. That is my interest. I do happen to know some rhenium and some osmium chemistries--rhenium is technetium's heavier family member and technetium and osmium are related by what's called a diagonal relation. Of course, any new undiscovered uses for technetium would probably lack commercial utility--who wants to use something touched by a radioactive catalyst?  Radioactivity carries enormous stigma--especially for organic life forms. But the world is changing. We are creating artificial life and intelligence in our own image.

How to assess what technetium might be good at?

Chemical Gnomonclature*

Scotoma is the technical term for the blind spot in our field of vision. Our brains interpolate the missing data so we don't perceive a black spot, but in fact we have two scotomas, caused by the lack of retinal cells where the optic nerve joins the retina (see link).

The Periodic Table is a reticulated array of data. In the mid 1930's, element 43 was still conspicuously lacking. Dmitri Mendeleev, that great Russian seer of visions and father of the Periodic Table, foresaw its existence and called it eka-manganese, meaning "one-after-manganese." Here's what the family of transition metals looked like in the mid 1930's:

Chemists sought eka-manganese unsuccessfully for 75 years after Mendeleev's prediction: their efforts are nicely summarized by van der Krogt. Of the fruitless efforts, those of Noddack et al. came closest, and they proposed the name masurium in 1925. Several Periodic Tables from that era even included Ma beneath manganese.

Unequivocal proof for element 43 appeared in 1937, after an Italian team led by Emilio G. Segrè  isolated it from radioactive samples of next door molybdenum which had been bombarded with deuterium nuclei at Berkeley. They named the new element technetium from the Greek τεχνητος, meaning artificial.
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*Gnomonclature is an homage to James Joyce who invented a literary device called gnomon to accentuate character or story element.  In the words of his character Stephen in A Portrait of the Artist as a Young Man:

Absence is the highest form of presence.

The absence of eka-manganese drove generations of chemists to search for it because it was there--somewhere.

The Frightening News First Heard In German...

Lise Meitner with Otto Hahn. Leitner, who was born Jewish, had fled Berlin that July 1938. She first spread the news of fission to the rest of the physics community.

Splitting the atom in 1938 was something wholly different than what had gone on with radiation since its discovery in 1896. To my mind, the news must have been like expanding the notion of arithmetic from simple addition and subtraction to suddenly include the concept of division. It really blew people's minds at the time. Soddy had explained how elements incrementally transmuted downwards in atomic number (subtraction) by shedding alpha particles and how they transmuted upwards (addition) in number by losing beta particles, but nobody was looking for this:*

original

In 1938, Otto Hahn and Fritz Straßmann bombarded uranium with neutrons and fished out the products. Neutrons were all the rage after their discovery in 1932 and physicists wanted to know what they did to all types of matter. Enrico Fermi had started this sort of work in Italy, but had been interrupted. It was only a matter of time before someone figured out what was going on. Hahn and Straßmann had expected to observe slightly lighter atoms like radium, actinium, and thorium; instead they observed the much lighter elements barium, lanthanum, and cerium:

Als Chemiker müssen wir aus den kurz dargelegten Versuchen das obengebrachte Schema eigentlich umbenennen und statt Ra, Ac, Th die Symbole Ba, La und Ce einsetzen. Als der Physik in gewisser Weise nahestehende Kernchemiker können wir uns zu diesem, allen bisherigen Erfahrungen der Kernphysik widersprechenden Sprung noch nicht entschließen. Es könnte doch noch vielleicht eine Reihe seltsamer Zufälle unsere Ergebnisse vorgetäuscht haben.

As chemists, we must rename [our] scheme and insert the symbols Ba, La, Ce in place of Ra, Ac, Th. As nuclear chemists closely associated with physics, we cannot yet convince ourselves to make this leap, which contradicts all previous experience in nuclear physics. A series of strange coincidences could still prove our results false.

This was the first published account of nuclear fission. Smart people realized that the exact chemical products required that more neutrons were coming out than were going in--this was soon verified and led physicists to realize that Leo Szilárd's chain reaction was now feasable. The news spread like fallout. And because it came from 1938 Berlin, the entire rest of the physics community panicked...and then they organized.**

Read more about the discovery of fission here.

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*A German chemist, Ida Noddack, had suggested as early as 1934 that "it is conceivable that the nucleus breaks up into several large fragments, which would of course be isotopes of known elements but would not be neighbors of the irradiated element"---but no one took her seriously.  link

**Another frightening fact was that the Austrians had cut off everyone else's supply of uranium from the original Czech mine--the same place Marie Curie had obtained her original samples in 1896.

Neutrons Made It Possible

Neutrons are everywhere, in everything, hiding in plain sight. Historically, they had to be imagined before they were detected because they were so hard to find. Rutherford had thought special "neutral pairs" of protons and electrons were inside atomic nuclei in order to explain why atomic weights varied and also to explain isotopes. To him, an alpha particle had four protons and two electrons instead of two protons and two neutrons and no electrons.

Certainly bearing a charge--being polarized--had made the earlier detection of electrons and protons easier because electromagnetic fields could deflect them. Their flight paths could be swayed. They could be attracted or repelled. Their charges gave them away and allowed them to be counted because they ionized things. Not so neutrons. Even today, neutrons are detected only indirectly via their effects on other signalling atoms.

At first, neutron radiation was confused with a more powerful type of gamma ray because it passed right through matter and with such ease--outdoing even gamma rays. But the new radiation did weird things to hydrogen-containing molecules like paraffin. And, they didn't do something that gamma rays did: they didn't spring electrons from metals like X-rays (the photoelectric effect). But the clincher was proving that the radiation had heft...mass. James Chadwick did that and won the Physics Nobel Prize the very next year.*

If neutrons have no polarity, no "handle," to steer them or deflect them, how are they channeled?  Mainly by projecting them through tunnels of neutron absorbing materials. Those that make it through have directional velocity. It sounds crude, but that's all there is.

At Los Alamos National Laboratory (LANL), there used to be an underground experimental station which resembled a spoked wheel. At the center, the hub, was a block of tungsten (I was told--of course I couldn't see it).  A proton beam impinged this target from above, creating a spallation of neutrons. Numerous tunnels led outwards from the hub like spokes on wheel. The tunnels were surrounded by paraffin and borax--materials with good neutron capture cross-sections. Each tunnel created a beam of neutrons terminated out at a "rim" of connected experimental stations.
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*The defining experiments are briefly described here.
Chadwick wrote in 1940 (after reviewing progress on the atomic bomb):

[I] realised that a nuclear bomb was not only possible, it was inevitable. I had to then take sleeping pills. It was the only remedy.

Crystalline Rot

When Marie Curie coined the term "radioactivity," a competing term--hyperphosphorescence--was thankfully never adopted. Hyperphosphorescence, while descriptively accurate--lacks simplicity.  Metamictization is another concept that needs a simpler term.

Crystals are highly ordered structures. The word "metamictization" refers to internal destruction, usually caused by radioactive uranium or thorium inclusions--their radiation destroys the crystal's integrity in a sort of rotting from within. "Stone cancer" might seem appropriate, but remember that cancer is unchecked growth.

"Crystalline rot" might work as a simpler term than metamictization because it conveys the notion of havoc wreaked from within--like an organized nation's structure.

Y R U Called Yttrium?

I am largely ignorant of yttrium's benefit to mankind. Element No. 39 sits near the parched southwest corner of the Periodic Table, not unlike the American southwest before the construction of the Hoover Dam.

Directly below yttrium in the chart are two pinkish blanks which are place holders for the lanthanides and actinides, two distinct families of elements I'll get to eventually. Yttrium behaves much like the lanthanides below it, another example of periodic rhyming. Yttrium presents in nature only as a trivalent cation, Y³⁺, as an oxide. Trivalent cations are hellacious electrophiles, meaning that they latch onto—and mostly won't let go of—electron lone pairs. Water is the most common and abundant nucleophile--hence my remark that yttrium sits next to a parched corner of the table--I mean its electronically deficiency. Yet I've heard that such cations, properly supported and kept away from water, react with the C-H bonds of aliphatic hydrocarbons.

Yttrium supposedly has an interesting name (yawn). At least five other elements were named after the same mine in Ytterby, Sweden. Van der Krogt has the story here.

Old color TV screens and computer monitors (CRT) used yttrium to create the red-colored pixels. CRTs are the kind of monitors that shoot beta rays at your face. They really are old school (dependable) technology. Good thing there's usually some thick leaded glass there to stop the beta rays and most of the X-rays.

"Don't call it transmutation. They'll have our heads off as alchemists"

The transmutation of elements was an ancient, discredited notion promulgated by alchemy (alchemy is to chemistry what astrology is to astronomy). Alchemists sought to turn base metals like lead into gold. They failed or were quacks and charlatans. And yet transmutation has always occurred naturally and has been practiced since 1917.

Natural transmutation was first discovered when Frederick Soddy, along with Ernest Rutherford, proved that radioactive thorium converted to radium in 1901. At the moment of realization, Soddy later recalled shouting out: "Rutherford, this is transmutation!" Rutherford snapped back, "For Christ's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists."

Transmutation became a fait accompli. But it was one thing to discover that atoms could naturally and spontaneously lose little pieces like an alpha particle or a beta particle or even a gamma ray. It was quite another thing to discover that atoms could add little pieces too.

In 1917, Rutherford projected alpha particles from radium decay through air and discovered a new type of radiation which proved to be hydrogen nuclei (Rutherford named these particles protons). Further experiments showed the protons were coming from the nitrogen component of air, and he deduced that the reaction was a transmutation of nitrogen into oxygen:

¹⁴N + α → ¹⁷O + proton

This was also the first demonstrative proof of artificial transmutation and the proton's existence.  All that was needed now was the neutron which led to division and multiplication.

Penetrative Insight

[continued in part from here]

Henri Becquerel and Marie Curie didn't understand the new type of rays they discovered--they just knew it was different. Unlike X-rays, the radiant energy could not be switched on and off (this is what Marie Curie meant by her term "radioactivity"-- something actively giving off rays).

The first clue to understanding radiation came from observing what it took to stop it. Like Roentgen did with X-rays before him, Rutherford also did in a systematic way. He discovered that opaque paper stopped some rays--and these he called alpha rays. A second more powerful ray escaped from behind paper sheathing but was stopped by thin metal foil or glass--these he called beta rays. A third class could be wrapped in many layers of different material and still the radiation leaked through--he called these gamma rays.  A student named Geiger invented the eponymous "Geiger counter" which enabled a facile detection and quantification of these studies.

Only later did he and others figure out that alpha rays were actually alpha particles and that beta rays were really electrons and that gamma rays were like x-rays but more powerful. The juxtaposition of alpha, beta, and gamma radiation gives a nice depiction of radiation being both particle and wave in nature:

Cleaning-up radioactivity

[I wanted to go full steam ahead with more Titanic posts but a couple unfinished posts on radioactivity (last month's mania) are clogging the pipeline]

Clive Cussler wrote a cold war thriller I read called Raise the Titanic. In his story, a unique element call "byzantium" is thought to be locked in a safe on board. The mineral is needed for a new weapon and sets off a clandestine race to get at it. The ship is refloated (nobody believed Jack Thayer's story that she had broken in two). There is also a Geraldo moment when the safe is opened which James Cameron must have copied decades later in his 1997 opus Titanic. I already noted how the story of fictional Rose Dawson was inspired by the real life Sheila Mitchell

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?

"Rutherford was an artist. All his experiments had style."

Ernest Rutherford (1871-1937)

Ernest Rutherford reminds me of Michael Faraday. Born in humble circumstances in faraway New Zealand, he travelled to the mother country to study physics. Like Faraday, equal opportunity earned him a place with the best of his day and this meant the Cavendish Laboratory at the University of Cambridge. Rutherford must have witnessed J.J. Thomson's discovery of the electron there in 1897 but there's no record of him taking part in that work. It didn't matter--he had enough in him for two careers in science and a Nobel Prize of his own. And one of Rutherford's great achievements was the accidental undoing of his mentor's plum-pudding model of the atom.

Rutherford's first independent work was the unravelling of radioactivity along with Fredrick Soddy.  More on this later. But first, I want to close a loop I opened a few posts ago by hinting that I had found an inconsistency. I was referring to Richard Rhodes' account of Rutherford receiving the 1908 Nobel Prize in Chemistry:

An eyewitness to the ceremonies said Rutherford looked ridiculously young--he was thirty-seven--and made the speech of the evening. He announced his recent confirmation, only briefly reported the month before, that the alpha particle was in fact helium. The confirming experiment was typically elegant. Rutherford had a glassblower make him a tube with extremely thin walls. He evacuated the glass tube and filled it with radon gas, a fertile source  of alpha particles. The tube was gas tight, but its thin walls allowed alpha particles to escape. Rutherford surrounded the radon tube with another gas tube, pumped out the air between the two tubes and sealed off the space. 'After some days,' he told his Stockholm audience triumphantly, 'a bright spectrum of helium was observed in the outer vessel.' Rutherford's experiments still stun with their simplicity. 'In this Rutherford was an artist,' says a former student. 'All his experiments had style.' 

~Richard Rhodes in "The Making Of The Atomic Bomb"

Rhodes' book is a favorite of mine and I've read it a couple times. But Rhodes makes no mention of Soddy and Ramsey's proof five years earlier that the alpha particle was helium. According to Wikipedia:

In 1903, with Sir William Ramsay at University College London, Soddy verified that the decay of radium produced alpha particles composed of positively charged nuclei of helium. In the experiment a sample of radium was enclosed in a thin walled glass envelope sited within an evacuated glass bulb. Alpha particles could pass through the thin glass wall but were contained within the surrounding glass envelope. After leaving the experiment running for a long period of time a spectral analysis of the contents of the former evacuated space revealed the presence of helium. This element had recently been discovered in the solar spectrum by Bunsen and Kirchoff.* link

This account essentially parallels the elegant (but later) experiment announced in 1908 by Rutherford and described by Rhodes with the exception of radium instead of radon as the source of alpha particles. However, my review of the 1903 Ramsey & Soddy paper cited by the Wiki actually describes a much different and less elegant experiment. link
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*Also, Bunsen and Kirchoff didn't find helium in the solar spectrum--Lockyer did: link

Strontium Builds Strong Bones

Naturally occurring rubidium is only weakly radioactive and unregulated, but manmade strontium-90 is practically a worst case scenario. Strontium-90 first acquired its bad reputation back in the 1950's when it, along with certain caesium and iodine isotopes, were identified in the fallout from nuclear weapons testing. Strontium-90 is also a decay product from nuclear reactors. The worst accidents involving strontium-90 both occurred in the former Soviet Union: Chernobyl in 1986 and the Kyshtym nuclear disaster in 1957. link

Strontium-90 decays relatively quickly (it's a beta-emitter) and is taken up in bones. Strontium "rhymes" with calcium and very much resembles it. Strontium is bone-seeking and can supplant and replace natural calcium. Calcium is the backbone of life and modern civilization: think skeletons & concrete. Ca²⁺ and Sr²⁺ are both small & hard and can interchange within living structure as oxides and polyoxoanions, e.g. phosphates.

But regular strontium, which is not essential to life, may partially redeem itself. Naturally occurring strontium is not radioactive and strontium therapy shows promise for the treatment of osteoporosis, though its use is controversial. link

Lastly, if the name strontium sounds weird it's because it was named after a Scottish town Strontian (Srón an t-Sithein) where it was first found. Van der Krogt tells the story of its naming here.

Doing the aftermath of Becquerel's discovery

[continuation in part from here]

Becquerel's discovery of uranium's radioactivity led to several immediate questions:

(1) Were other elements besides uranium radioactive?
(2) What is radioactivity? Was it it like X-rays?
(3) How to square radioactivity with the Law Of Conservation of Energy.

In the mid 1890's the Periodic Table looked like this:

Original

Note that the noble gases (which had just been discovered--were absent). Also, nickel and cobalt were incorrectly ordered under group VIII as I mentioned here.

Marie Curie found that thorium (an element known since 1828) was radioactive in 1898.  There was a priority dispute with a German chemist, Gerhard Carl Schmidt which I'm still reading about. Thorium's importance briefly eclipsed uranium's, because the latter was in short supply until more sources could be found. Curie, along with her husband Pierre, began extracting uranium from samples of impure Czech pitchblende. They discovered that the purer they got the uranium, the stronger the radioactivity was in the concentrated waste left behind. This told them that something else was in there. They discovered polonium in July and radium in December of 1898, adding two new elements to the chart shown above.  In this way, radioactivity became a tool for discovering new elements.

"Radiation...You Hear The Most Outrageous Lies About It"

A favorite line from a favorite movie--Repo Man:

So in delving into the early history of radiation, I think I'm fact-checking myself into outing a falsification.

More later.

meanwhile, added:

Early radiotherapy

Decay Matters

Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world,
The blood-dimmed tide is loosed, and everywhere
The ceremony of innocence is drowned;
The best lack all conviction, while the worst
Are full of passionate intensity.

~William Butler Yeats THE SECOND COMING (1919)

Radioactivity, even more than X-rays, shook up physics at the end of the 19th century. Men and women of reason gradually realized that atoms do break down--that atoms were not indivisible as the name implied but that they could decompose and decay into other kinds of atoms. And when they do break down radiation and lots of mc² follows.

The man-made sun on earth...

...was first preceded by a moment of darkness. Nuclear weapons were contrived invention, but the phenomena behind them are quite natural. The Sun is our main source of energy--directly or indirectly--and at first its light was thought necessary for radioactivity.

Henri Becquerel (1852-1908)

Henri Becquerel was fascinated by phosphorescent materials--materials which glowed in the dark after exposure to sunlight--including uranium salts. In 1896, he knew of Roentgen's discovery the previous year--the discovery of X-rays--and he wondered if phosphorescent uranium would give off penetrating rays after exposure to light.* Here he describes his eureka moment:

One wraps a Lumière photographic plate with a [Ag] bromide emulsion in two sheets of very thick black paper, such that the plate does not become clouded upon being exposed to the sun for a day. One places on the sheet of paper, on the outside, a slab of the phosphorescent substance, and one exposes the whole to the sun for several hours. When one then develops the photographic plate, one recognizes that the silhouette of the phosphorescent substance appears in black on the negative. If one places between the phosphorescent substance and the paper a piece of money or a metal screen pierced with a cut-out design, one sees the image of these objects appear on the negative...

The shadow of a small copper cross is visible

One must conclude from these experiments that the phosphorescent substance in question emits rays which pass through the opaque paper and reduce silver salts.

But further experiments led him to doubt the necessity of sunlight and to abandon this hypothesis. Later, he reported:

I will insist particularly upon the following fact, which seems to me quite important and beyond the phenomena which one could expect to observe: The same crystalline crusts [of potassium uranyl sulfate], arranged the same way with respect to the photographic plates, in the same conditions and through the same screens, but sheltered from the excitation of incident rays and kept in darkness, still produce the same photographic images.  March 2, 1896

Becquerel's students, Pierre and Marie Curie, went on to discover two new elements, radium and polonium. Marie Curie coined the term "radioactivity" to describe the elements' natural property of begetting penetrating rays.

[story continues]
_______________
*Becquerel may have been aware of Niepce de Saint-Victor's near discovery of the same phenomenon a generation earlier. link