Star stuff 'R' us

 kw: book reviews, nonfiction, science, chemistry, cosmology, biology, philosophy

Let's take powers of ten, in time, looking back to the beginning:

• 13.8 billion years ago, everything began. Starting with the "Big Bang", or whatever it was, in some tiny fraction of a second all energy and matter appeared and sorted themselves out, becoming something like 10⁸⁰ "elementary" particles; either protons, neutrons, and electrons, or electrons plus quarks. Initially something like a thousand times that many particles of both "matter" and "antimatter" formed, and some tiny imbalance resulted in all the matter presently in existence. At least the visible or potentially visible stuff. This is accompanied by a much greater number of bosons such as photons.
• 1.38 billion years ago, we find that our Galaxy has appeared (10 billion years earlier) and then our solar system (just over 3 billion years earlier), and then once Earth settled down, life that either began as bacteria or soon became bacterial and archaean (AKA prokaryotes); and finally eukaryotic cells (larger cells with a nucleus) had arisen, such that almost anything big enough for us to see was composed of them (though they were, as we are, vastly outnumbered by the tinier prokaryotes).
• 138 million years ago it's already getting late in the Age of Dinosaurs: the familiar Tyrannosaurs plus Triceratops, Iguanodon, and sauropods such as Argentinosaurus stalked the land, pterosaurs flew hither and yon, and the seas were filled with ammonites (like an octopus with a big, coiled shell), mosasaurs and plesiosaurs. Flowering plants had recently evolved and were spreading everywhere.
• 13.8 million years ago it's the middle of the Miocene; mountain building is going on, and the continents have formed something similar to their modern configuration. A minor branch of mammals, the primates, has produced a few species larger than a rat, up to the size of a squirrel monkey.
• 1.38 million years ago, it's the middle Pleistocene. The ice ages began a million years earlier, and the Gorilla-Chimp-Hominin divide occurred in the range of 6-9 million years earlier. Homo erectus appeared 2 million years ago and by 1.38 million, was speciating into a few hominid species, although Neanderthals had yet to appear.
• 138,000 years ago, Neanderthals are all over Europe and Asia, while all archaic Homo sapiens are still in Africa.
• 13,800 years ago: It's been about 20,000 years since Neanderthals became extinct (or assimilated with H. sapiens). It's the middle of the Late Glacial Interstadial, a warm period that lasted about 1,800 years, followed by the colder Younger Dryas era. Humans are already on every continent except Antarctica (and maybe there also at times!). 
• 1,380 years ago: As I write this, that would be 643 AD (or CE), almost 160 years before Charlemagne unified the Holy Roman Empire. Anything resembling "science" is a millennium in the future.
• 138 years ago, in 1843, Queen Victoria had recently begun her 63-year reign; Louis Pasteur began to teach; the first Opium War had just ended in China; the first immigrant from Japan arrived in the United States. The germ theory of disease is still 50 years in the future.

That's a good place to stop the timeline, because 13.8 years ago almost anyone who can read this was alive and can remember numerous world events. It's also a useful backdrop to the much different history developed in What's Gotten Into You: The Story of Your Body's Atoms, from the Big Bang Through Last Night's Dinner, by Dan Levitt. 

Note that there is no question mark in the title; it is not a question but a statement, an affirmation. Wind back to 13.8 billion years ago, and the first atoms were produced soon after, very soon. They are nearly all still with us. If we pull back to look at the Universe as a whole, nearly 75% by mass is hydrogen and 25% is helium. About 1% is everything else, all the other 90-odd elements that have been formed since stars began to shine. Subtract that 1%, and you have the composition of the Universe 13.7 (or maybe 13.6) billion years ago.

The core of an atom is its nucleus. For hydrogen, it's almost always a single proton. Two other forms (isotopes) of hydrogen have one and two added neutrons, respectively. Helium almost always has two protons and two neutrons; a rare isotope of helium has one neutron. Nearly all the atoms of hydrogen and helium that were produced in the extremely early universe are still in existence. About 1% of them have been compounded (fused) into other atoms, of almost 100 elements and several hundred isotopes. The book tells about the step-by-step discovery of how the stars "cooked" the other elements. Without that cooking, there would be no carbon, oxygen, nitrogen, and other elements that it takes to make Earth and the other planets, and also all living things including us. Note that the atoms in the stars, in planets, in us, probably don't have their "original" electrons. Those can move from atom to atom, and chemistry is what we call the movements of electrons.

So, what has gotten into you, and into me? Primarily water (60+% of our bodies are water), composed of hydrogen from the early universe and oxygen cooked up in a large star that later blew up as a supernova. In whatever way elements were produced in stars, the way they got back into the universe to become planets and people was by supernova explosions…well, some amount of lighter elements got out of stars in a more gentle way as they shed their outer layers in the late stages of being a red giant. But anything heavier than iron had to come from a supernova, created during the eruption, and most elements heavier than oxygen also were expelled during supernova eruptions.

Chapters in the book detail the discoveries of organic chemicals, and RNA and DNA, and other molecules of life, a story that is still unfolding. The story of all the parts that have to work together for a cell to function is one of the most complex tales there is. Every cell in your body is as complex as Chicago, but operates millions of times faster. Even bacterial cells are only "simpler" by comparison: one cell of the "simple" bacterium E. coli contains 20,000 "factories" called ribosomes, that produce proteins under the direction of bits of RNA copied from the DNA "library". And the same cell contains thousands of other active bits called organelles with sundry functions. A typical cell in our body is 15,000 times as large (in volume; 25x the diameter) as an E. coli cell, and contains dozens of organelles that the bacterium doesn't have (or need). All are made from either primordial hydrogen or from the forty or so other elements, ejected by supernovae, which were brought together on this planet to become living things. THAT is what has gotten into us.

Reading this book was joyful. I hope you read it and will agree.

Elements - the rest of the stories

kw: book reviews, nonfiction, chemistry, physics, elements, stories

A perfectly ordinary spoon. It looks and feels like aluminum, just a bit heavier…unless you hold it too long. But the person who handed it to you urges you to immediately mix your coffee with it. In a matter of seconds, you have in your hand only the handle, which soon begins to melt and also drip into the coffee cup! What is this?

Gallium, which is chemically very similar to Aluminum, is nearly twice as dense, but still much less dense than stainless steel or silver. A spoon made of it feels light. Its melting point is 85.6°F (29.8°C), and your hand is several degrees warmer than that (unless you've just been outside throwing snowballs with bare hands). If you had held the spoon in your hand more than a few seconds, it would have begun to melt. Gallium and Mercury are the only two metals that you can touch when they are molten without getting a serious burn. There are hundreds of YouTube videos showing gallium spoons, and other objects, melting in warm water or into the hand of someone. It is not toxic, while mercury is very toxic.

Stories about gallium and other elements—all of them, in fact—fill the pages of The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World From the Periodic Table of the Elements, by Sam Kean. "The Periodic Table!" you say, perhaps with a shudder. Shades of Junior-class Chemistry in High School rise up to haunt you.

The Periodic Table of the Elements isn't (only) an instrument of teen torture. It is very useful. Just to lay some groundwork, and to get it out of the way, here is a simple version as seen in the Gallium page of Wikipedia:

The version you most likely remember (or try to forget) probably had 18 columns, not 32, with a separate pair of lines below with elements running from La to Lu and Ac to Lr (or maybe only as far as Cm or Bk with the rest of the boxes blank). This table incorporates all the elements into a single table and adds the convenience of color coding of elements with similar, or related, chemical properties. Gallium (Ga) is highlighted, right below Aluminum (Al).

The chemical similarities between certain elements led to the development of the first Periodic Table by Dmitri Mendeleev in 1869. He was not the first to notice the similarities, but he was the first to use the "periods" (the columns in the table and their repeating nature) to predict the placement and chemical properties of several new elements. As these elements were discovered, one after another, the table was established, as was Mendeleev's fame.

Early chapters of The Disappearing Spoon outline Mendeleev's discovery and that of the first handful of elements, including the ones that confirmed that his table was trustworthy. Other chapters group the elements by the kinds of stories that swirl around them (or did when they were newly known). For example, Chapter 9, "Poisoner's Corridor: 'ouch-ouch'", begins with the sad story of cadmium (Cd) in a Japanese mine. Waste material rich in Cd and zinc (Zn) was a byproduct of the precious metals that the Shogun desired. Later, when Zn was found useful, the waste tailings were re-mined, of course without any protective measures. You'll see Cd in the table above, just below Zn, which is next to Ga. Being chemically similar, Cd is found with Zn, but it is not totally identical so acid roasting can separate the two metals. Cd-rich waste, now in water-soluble form, was cast away and got into the streams. People downstream who drank the water got "Itai-itai!" disease. "Itai" is Japanese for "Ouch!" Cd weakens the bones and later causes the kidneys to fail. Early death was nearly universal, either because of infection from compound fractures, or from kidney disease. Thallium (Tl) and Bismuth (Bi) have their own stories to tell, of chemical "improprieties". Strangely, in the right compound, Bi is not toxic, and is the basis for Pepto-Bismol! You can drink it to help an upset stomach. Tl, on the other hand, is horrific! Read about it.

Two other elements, Thorium (Th) and Americium (Am) poison in a different way. They are radioactive. They bracket the range of the more common radioactive elements. The most stable isotope of Thorium, Th-232, has a half-life of 14 billion years, nearly three times as long as Uranium-238. As metals, Th and U are safe to handle for short times (I have done so). Am-241 is much more dangerous than radium (Ra). Its half-life is 432 years, while that of Ra-226 is 1,600 years. However, while radium decays to radon (Rn), the radioactive gas that we try to keep out of our basements, americium decays to other metallic elements, which stay put. Thus it can be used in smoke detectors, so you probably have a few micrograms of Am-241 in your house!

Chapter after chapter, the author tells us story after story of how elements were discovered, and/or how they are used, and curious facts about them. The phrase "Mad as a Hatter" (and the Mad Hatter of Alice in Wonderland) indicate the gradual insanity caused by using mercury (Hg, for "hydrargium" or "liquid silver") to process felt for hat-making. And some new elements have been tried as love potions, with universal lack of success.

So, maybe you hated high school chemistry, or maybe, like me, you loved it. Regardless, the stories behind the elements, and their arrangement into the Periodic Table, are enjoyable. The book is well worth a read.

I have to close with a quibble about near-homonyms and their misuse. Referring to metals such as Cd being dissolved into ground water, the author uses both "leech" and "leach", where only "leach" is proper. The other word refers to a parasitic animal, or your cousin who is always borrowing from you. Then, he describes the damage and illness caused by some elements as being "ravished". The right word is "ravaged". To ravish is to rape, though the word has other uses, but it is definitely not a synonym for ravage. And finally, describing physical characteristics of some animals, "waddles" appears. The author meant "wattles", the folds of skin on the neck of a turkey or an elderly person or dog. "Waddle" is a verb, not (or very rarely) a noun, and describes walking with a distinct swaying motion.

Well, let's forgive Sam Kean for such minor crimes. His writing is enjoyable and the stories he has unearthed are fascinating. I bought this e-book as part of a three book set, so it won't be long until I review the third (I already reviewed The Tale of the Dueling Neurosurgeons).

Chemistry for those who don't know any

kw: education, chemistry, basics

Think of a scientist and what do you see in your mind's eye? Probably someone in a white coat mixing chemicals. Chemistry is the bane of humanities majors everywhere, because you have to take Chem 1 with a (barely) passing grade to get on with your major. (Those with a sharp eye will note that the cylinder being poured from is about to dump all its contents at once!)

So let's knock out a few basic concepts to jump-start your education. First the ultra-quick version:

Chemistry studies how atoms share or exchange electrons. Of roughly 100 kinds of atoms, a few—twelve, to be exact—have one or two "loose" electrons that are easy to strip off, while another twelve have room for one or two more, and will easily plunder those loose electrons. Some others can either gain or lose three, four, or even five electrons. The rest typically share electrons. Chemistry is learning all the ways this can happen, and which elements behave in which fashion.

For more, read on. We begin with Electrons.

Electrons

Electrons are particles that make up the outer "skin" and "flesh" of atoms. What we usually mean when we say "chemistry" is properly "electron chemistry". There is also nucleon chemistry, plus other subdisciplines such as crystal chemistry and organic chemistry. The odd thing is, you first have to know a little about nucleon chemistry to get a framework to learn electron chemistry.

Nucleons and Elements

Perhaps you have heard that there are 92 "natural" elements, or maybe, as I wrote above, that there are "about 100 elements". There are actually 90 elements called "naturally occurring". That is because, although the heaviest natural element is Uranium, #92, the elements numbered 43 and 61 are not found in nature, for reasons we'll soon get into.

Nucleons are the particles that make up the nucleus: Protons and Neutrons. The number of protons in a nucleus determine what element it belongs to. For a nucleus to be stable (and the "what for" about this is a major subject of nucleon chemistry) there need to be neutrons present also. Only one element has no neutrons in its nucleus, Hydrogen. An atom of hydrogen, the simplest and lightest element, has one proton and one electron, and nothing more. Every other kind of nucleus has at least one neutron, and with only one exception, the number of neutrons is at least as large as the number of protons.

The main item of nucleon chemistry that you must know is that the Atomic Number is the number of Protons. The term Atomic Number is used everywhere. It is also extremely useful to understand that radioactivity expresses the tendency for certain combinations of protons and neutrons to break apart in one way or another. A very few kinds of "unstable" nuclei are nearly stable and last for millions or billions of years. Uranium is one of these.

Nuclei of elements #43 (Technetium) and #61 (Promethium) are always unstable, in every variety, no matter how many or how few neutrons are in there with the protons. In this case, "unstable" means having a half-life short enough that every single atom of these elements that may have existed billions of years ago when Earth was formed, has decayed. Half-life is another very useful term, though mainly in nucleon chemistry. For a bunch of any specific, unstable kind of nucleus, the half-life is the time it takes for half of them to decay. Lots of uranium (originally produced when big stars blew up billions of years ago) is still here because its half-life is about 4.7 billion years.

The fundamental tool for understanding electron chemistry is a table in order of Atomic Number, that is arranged according to how electrons pack together in each kind of element: the Periodic Table.

Periodic Table

Get ready for it! I am about to explain this monstrosity:

The columns are arranged the way they are because elements in a column have similar chemical behavior. Down the left side, for example, the six elements Li, Na, K, Rb, Cs, and Fr all have similar chemical behavior because the outermost electron is "loose" and easily lost to more acquisitive elements. Hydrogen is special; though it can both lose and gain an electron, it also participates in a third kind of sharing bond we'll describe later.

Each row represents an electron shell, which fills from left to right. The rightmost column, topped by Helium (element #2) contains all the elements with a completely filled shell. This is the group of elements with the easiest chemistry: They don't participate in chemical reactions! But right next to them we find F, Cl, Br, I, At, and the "artificial" element currently called Uus (Un-Un-Septium, a fake Latin term for 117). They all have an outermost shell that is nearly filled, but is ready to grab an electron from another element that has a "loose" one available.

The rows are different lengths because the shells have different capacities. It takes some learning in quantum physics to comprehend what electrons are doing (as much as that may be possible!). Here is the simple explanation:

• Electrons come in pairs.
• The first shell is filled by a single pair, thus Helium has a filled shell. This filled shell is the core of all heavier elements.
• The shells of all elements other than Hydrogen and Helium have sub-shells.
• The sub-shells were discovered by spectroscopy, and are called, for historical reasons, s, p, d, and f.
• Sub-shells increase by odd numbers of electron pairs:
• p has 3, so s+p = 4 pairs or 8 electrons.
• d has 5, so s+p+d = 9 pairs or 18 electrons.
• f has 7, so s+p+d+f = 16 pairs or 32 electrons.
• Shells 2 and 3 have s+p only; 4 and 5 also have d (thus the lower-middle block); and 6 and 7 also have f (shown as the extra stuff below the main table).
• The placement of the rows shows that the d sub-shell fills before the p sub-shell, and the f sub-shell fills before d.

Note that the number of electron pairs in a completed shell is a square number: 1, 4, 9, 16. The next square would be 25, though no elements currently existing make any attack on that shell.

All the elements from 93 to 118 have been produced in nuclear reactors and particle accelerators. With element #118, the seventh shell is filled, so once elements #119 and greater are produced, an eighth shell will begin to fill. This is expected to have a new sub-shell, usually called g. It can contain 9 electron pairs. It is likely that the g sub-shell will begin to be filled with element #121, but we will only know this for sure if element #121, or a heavier one, has a long enough half-life so the electron arrangement can be studied before the whole sample decays away.

Bonding

When one atom takes control of the loose electron given up by a different atom, or when atoms share electrons, we talk of a chemical bond. To discuss this, a version of the Periodic Table with different highlighting will be helpful:

You know that term "alkali"? It refers to substances that neutralize acids. The two columns of elements at the left, in lavender and blue coloring, are called the Alkali Metals (lavender) and the Alkaline Earth Metals (blue). The ones with an odd atomic number have one loose electron, and the even ones have two loose electrons. They participate in compounds that tend to be alkaline; in some cases, the compounds are so caustic they will remove your skin.

Now, at the far right, as I mentioned above, the elements in the last column do not combine chemically with others. A few very extreme experiments have been done to force them into unstable chemical compounds. We call them the Noble Gases. They, and four other elements in which the lettering is dark green colored, are gases at "room temperature", defined for chemists as 25°C or 77°F.

The elements in the next column, with beige coloring, are called Halogens. "Halogen" is from the Latin word for "salt". They like to glom onto loose electrons. Any of these reacted with hydrogen will form a strong acid, but when paired with one of the Alkali Metals or an Alkali Earth Metal, they form stable salts. Two of them are usually gases, one is a liquid (Br, with dark blue letters), and the rest are solids. They are a major part of a group also called Non-Metals.

Hydrogen plus the other elements in orange coloring are the rest of the Non-Metals. In element form, solidified at low temperature in the case of Nitrogen and Oxygen, they are insulating solids that look like soft ceramics. While Oxygen and those below it tend to snatch two loose electrons whenever possible, they also participate in the sharing bond I mentioned earlier.

The elements with brown coloring are called Semi-Metals. In element form, they are semiconductors, and one in particular, Si or Silicon, forms the basis for most electronic circuits. The lime green colored elements are Metals that are either semiconductors by themselves, or form semiconductors when alloyed with Semi-Metals.

All the rest of the elements in the main part of the table are colored light yellow, and are Metals. The top row of them, from Scandium to Zinc, are the Transition Metals. "Transition" refers to their similar chemistry. They all have a filled s sub-shell and an empty p sub-shell, and from 1 to 10 electrons in the d sub-shell, which is "hidden" beneath the filled s sub-shell. However, those two outermost electrons can act as loose electrons to combine with Non-Metals or Oxygen, and frequently one of the d electrons will also do so. Thus, they have more complicated chemistry than those to the extreme right or left. The three pale yellow rows below behave a lot like the Transition Metals, but it is harder and harder to get them to react. In particular, Platinum and Gold (Pt and Au) are very resistant to participating in chemical activity, as are the elements directly beneath them, though those are radioactively unstable and are very short-lived.

The Transition Metals are useful to living things in various amounts, usually quite small amounts. Even Iron (Fe), the most abundant metal in our bodies, is present as 4-6 grams in an adult human, or less than 1/100 of a percent. The heavier metals are called "heavy metals", particularly in medicine, because they are all toxic. Lead (Pb) is the most familiar toxic metal.

Ionic Bonds

The shift of one or more electrons between strong "electron donors" such as Li or Ca, and "electron acceptors" such as Se or Cl, produces an Ionic Bond. This kind of bond is strong in the pure solid, but is pulled apart in water to dissolve salts such as LiCl, CaBr2, or MgSe. However, salts with S or Se are poorly soluble compared to salts with Halogen elements "on the right". In water solution, the elements that have lost electrons are + ions, and those that have accepted electrons are - ions.

Covalent Bonds

Electron sharing in which two atoms form a strong bond to fill their outermost shell produces mainly insoluble compounds held together by Covalent Bonds. The Non-Metals, when in elemental form, usually exist as paired atoms sharing one or more electrons. The simplest example is ordinary Hydrogen:

Here the electrons are shown as dots. The shared electrons satisfy the s sub-shell of both atoms.

Most elements can participate in covalent bonds. The most versatile is Carbon, which has 4 outer electrons, and thus room for 4 more. It prefers to share a covalent bond in 4 directions. This makes it the most versatile in its chemistry, and a huge discipline, Organic Chemistry, is the study of carbon chemistry. Where a chemist who studies inorganic chemistry will become familiar with thousands or tens of thousands of chemical compounds, the number of organic compounds so far known exceeds 50 million.

The Take-Away

So, what do you really need to know to be ready for Chem 1? Or, just to be at least glancingly familiar with the subject? Chemistry is about the ways atoms transfer or share electrons. The outer electron shell of an atom can have between 1 and 8 electrons. The more promiscuous atoms, mainly Carbon, Nitrogen, Sulfur and Oxygen, induce the other elements to form complex molecules. In the absence of these four, most compounds are simple and easier to study.

Of a hundred all is made

kw: book reviews, nonfiction, chemistry, elements

If you were to touch molten aluminum, you'd lose some skin, at the very least. But there is an aluminum-like metal, about twice its density, but less dense than pewter or tin, that you can hold in your hand, where it will gradually melt into a shiny puddle. It isn't mercury, but gallium, and it melts at just under 30°C, or 85.6°F. This makes it amenable to a chemist's practical joke. Cast an ounce or two of it into a teaspoon, and bring it out with a serving of tea on a cool day. When your friend attempts to stir in some sugar or cream, the spoon will vanish into the tea! Do stand by, and prevent your friend from drinking the tea at that point; gallium is not strongly toxic, but ingestion is a rather bad idea.

Thus the title of the book, The Disappearing Spoon: and Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements, by Sam Kean. While early sections of the book introduce the elements and the periodic table and its history in a pretty regularized way, most of the book is a cross between rummaging through the intellectual attic and a topical, eclectic story-fest that manages to introduce us to every element by the end. That includes the newest members, Roentgenium (Rg; 111) and Copernicium (Cn; 112), and some others that, though long known, have never been seen, such as Francium (Fr; 87). In the latter case, a visible amount of the element's most stable isotope, ₈₇Fr²²³ with a half life of but 22 minutes, would probably kill you within the first few seconds of viewing. It is 38 million times as radioactive as Radium.

Fortunately, most elements are more prosaic, frequently with lively or even colorful chemistry, but with little tendency to strike you dead upon sight. The regularities in the elements' chemical nature underpin the structure of the periodic table. Ever wonder why it is called "Periodic"? Even many who have taken a chemistry course or two may not be clear on this. Here is a blank table, such as those used for dreaded quizzes, because the clues are in the table's shape:

The term "periodic" stems from the regular repetition of chemical properties as you advance through the elements. There are eighteen columns to the main table, plus fourteen in the added double row below. If those were inserted where the little gap is near the bottom, the table would have 32 columns. But it is the way in which each pair of rows lengthens that reveals something that is only explained by quantum electrodynamics—and by "explained", I mean the "what" of it, not the "how" or "why", which remain wholly mysterious.

In all the natural elements, and in all fabricated elements up to number 120, electrons are nested in shells and sub-categorized into four kinds of sub-shells called orbitals. The rightmost column in the periodic table contains those elements which have completely filled shells, while the first column contains those with completed shells, plus one electron. This lone electron gives these elements a strong similarity; they can rip the oxygen right out of water, and as you go down the column, they get more violent about it. But the elements with filled electron shells will have none of it. Only a few of them, under extreme duress, have been persuaded to form fragile compounds. Ordinarily they are aloof from chemistry, and are called the noble gases as a result.

The odd shape of the table is due to the way orbitals enter the picture; each has a letter with historical import, and a capacity for a finite number of electrons. They are designated s (2 electrons), p (6 electrons), d (10 electrons) and f (14 electrons). These letters are based on an old spectroscopists' convention, in which spectral lines caused by electron jumps that terminate in the various orbitals are denoted "sharp", "principal", "diffuse", and "fundamental". Highly-excited gaseous atoms can have even higher orbitals, which are just called g, h and so forth. But no known elements fill such orbitals in a stable state (yet).

From the second row onward, the s and p orbitals together form the "valence shell" that controls the principal chemical nature of the element, though the presence of other orbitals in deeper shells modifies it. Thus, row 1 contains just two elements, hydrogen (H; 1) and helium (He; 2), with only s electrons. The next eight elements fill first the s orbital then the p orbitals (there are three, each holding just two electrons, to total the six mentioned above). The following eight elements repeat the pattern.

After elements 19 and 20, however, the pattern changes. For reasons unknown, but mathematically explained by quantum mechanical equations, the five d orbitals "want" to be filled first, before the p orbitals. This pattern occupies the fourth and fifth rows. Then in the sixth row, we find that the f orbitals (seven of them) get filled first, then the d orbitals, then finally the p orbitals. The seventh row is the same. All those elements that occupy the middle ten columns characterized by d orbital filling are called "transition metals", because their chemistry makes a transition from oxidizing at one end to reducing at the other. The lower section, two part-rows of fourteen columns, are called first "rare earths" above then "rare earth-like" below, and have such similar chemistry that obtaining any of them as the pure element is nearly impossible (a mass spectrometer is the most effective method).

The table shown has room for 118 elements. To date, 112 have been unambiguously found or produced. Scientists, and the author, have speculated about finding quasi-stable elements with atomic numbers (proton number, in other words) greater than 118. What happens in the eighth row, assuming enough of an element could be accumulated long enough to scope out its chemistry? Here is a point that I've never seen discussed. Element 119 will have a single s electron in its eighth shell, and 120 will have two. Then what? Here, quantum mechanics predicts the intervention of a new orbital, which we can call g, still following the spectroscopists. Assuming the nine possible g orbitals all fill first, before the f orbitals get any electrons, there will be the need for another "moat" of length 18, below what is already shown. Were the table to be assembled with all elements in order, it would at that point be fifty columns wide.

How far can it go? As the author explains, the velocity function of the electron is described by a "fine structure constant", which has a value just a whisker greater than 1/137. Once the number of electrons surrounding an atom reach this number, the electrons in the innermost s orbital will need to exceed the speed of light! Maybe so, maybe not. I suspect people now living will be around when elements with atomic numbers approaching 137 are synthesized. Whether such elements are possible or not, the attempt will cause rewriting of our physics books.

That is quite a digression from a few opening chapters, plus a little speculation on my part. Most of the book is the stories of how all this was put together, by Mendeleev and others, and even more how various elements have played a role in world events, or declined to do so. Consider Ruthenium (Ru; 44). A white metal very similar to its neighbor silver, (Ag, 47), though harder, it was considered useless until the Parker Pen Company decided to produce a really luxury fountain pen, the Parker 51, with a gold nib. Gold is soft, so the very tip was an alloy of 96% Ru and 4% Iridium (Ir; 77), which hardened it further. So far as I know, its only other uses are as a minor alloying element, and it is seldom considered essential. While the Parker 51 didn't change the world, it was "the" accessory of every powerful person from 1944 until fountain pens were superseded by ball point pens a generation later.

The elements that changed the world the most, uranium (U; 92) and plutonium (Pu; 94) are known primarily for their damaging potential, as the stuff of bombs. Yet they (nearly all U) quietly drive a couple of hundred power generation plants around the world, keeping the air conditioners of millions of people running.

The topical sections of the book cover the gamut of human history and endeavors. While the "heavy metals" such as lead are in the news these days (can you believe we used to burn a lead compound with our gasoline?!?), there is a "poisoner's corner" from arsenic (As; 33) down and to the right, that contains the really bad actors. Arsenic sits below nitrogen (N; 7) and phosphorus (P; 15), such that its chemistry allows it to substitute for phosphorus when it gets into us, gumming up the energy-producing machinery that keeps us alive. This is because the As ion is larger than the P ion, so things get stuck. Interestingly, below arsenic we find antimony (Sb; 51), which is reasonably safe to handle, and used to be used in type metal. It and gallium (Ga; 31) are the only two metals that freeze into a solid less dense than the liquid. The Sb atom is too big to substitute for P, so it doesn't poison us the way As does. Next down we find bismuth (Bi; 83), so innocuous it is safe to ingest (there is a lot of it in Pepto-Bismol!). By the way, the most stable isotope of Bismuth, ₈₃Bi²⁰⁹, was recently found to be very slightly radioactive, but with such a very long half life—between ten and twenty billion billion years—that a gram of it will experience only about one decay per day.

The next column over is just the reverse. Oxygen (O; 8) and sulfur (S; 16), which are required for life, sit just above selenium (Se; 34). A tiny bit of selenium is an essential nutrient, at least for most mammals. But a lot of it damages the brain, leading to the designation of Se-bearing plants as "locoweed". But cattle love it, preferring the great high it gives, even as it kills off the brain. Ingested selenium also smells bad, so that it is sometimes called "stinkelenium". Next below Se we find tellurium (Te; 52). Not too toxic, but just a little of it will give you such stinky breath and bad BO that it will be years before your social life recovers. Then, next down, there's polonium (Po; 84). Always radioactive, with a very short half life and thus very strong activity, it is easier to make this stuff these days than to extract it from uranium ore. It was named in honor of Poland by Marie Curie, but the world simply yawned. Poland has usually not even been there, though these days it looks like it'll endure for a while. But polonium became famous when it was used to poison a former Soviet spy. A few micrograms sprinkled on some sushi were all it took to do him in.

I guess I simply have to wrap up. This is one book I could go on reading, if only it were longer (It is only 376 pages, endnotes included). I have a really geeky desire to repeat all the stories, but it is for the author to shine, not me. I had to slow myself down so as not to miss things. It is a real page-turner. The introductory chemistry that starts the book eases any reader into the meat of the book, so I am sure it is accessible to an audience much wider than chemistry addicts like myself. More than any popular book about chemistry, it shows how chemistry is geometrical in nature (remember that bit about "big" arsenic messing up the phosphorus works). This is even more true of organic chemistry, which is only slightly touched on in this book (hint to Sam Kean: You could do book after book about interesting families of organic compounds!). Now I regretfully lay it aside to take up the next book on my nightstand.

A word few need

kw: lexicography, chemistry

I learned a new word today: thermomorphic.

Used in the expression "thermomorphic catalysts".

By itself the word thermomorphic just means "temperature-mediated change in form". We all know an example, a piece of ice melting. That is the key to the meaning here, except in the other direction, of water freezing to ice.

Why is it applied to catalysts? There are two great classes of catalysts in chemistry, homogeneous catalysts and heterogeneous catalysts. Each has virtues and each has drawbacks. A homogeneous catalyst is in the same phase as the materials being reacted. Usually this means that everything is in liquid form. This has the great virtue that a bit of stirring will accomplish intimate contact between the catalyst and the reactants (reacting materials). The reaction runs at a maximum rate. But it has a significant drawback, that it is hard to get the catalyst out of the reacted product. Usually, the separation is accomplished by distillation or some kind of absorption separation.

Heteregeneous catalysts are in a different phase from the reactants. Usually, the catalyst is a solid and the reactants and product are liquids (at the temperature of reaction). It is easy to separate the catalyst from the product, just by filtration. But the drawback is that intimate contact during the reaction is harder to maintain, and the reaction is slower and perhaps not uniform everywhere.

Enter the thermomorphic catalyst. It is liquid at the reaction temperature, and turns solid when the completed product cools, but before the product itself freezes. So you run the reaction at a high temperature, cool it partway and filter out the catalyst, then cool the product further if needed. I call that neaty-keen.

We are made of poison

kw: book reviews, nonfiction, polemics, chemistry, toxins

I would call The Body Toxic: How the Hazardous Chemistry of Everyday Things Threatens Our Health and Well-being, by Nena Baker, required reading on a level with Silent Spring. We are no longer dependent on the "canaries in the coal mine" to indicate our risk; we are ourselves losing our "song".

The developed world has had a hundred-year love affair with chemical conveniences, and now we can see that they are false lovers. For a window into your own risk, go to CDC's biomonitoring project and download the Third National Report on Human Exposure to Environmental Chemicals, or its summary; both are free downloads in pdf format.

Ms Baker is wise enough to focus on just five bad actors that are currently found in the environments, and bodies, of nearly every American resident: atrazine (an herbicide), phthalates (plasticizers in cosmetics), PBDE's (fire retardants), Bisphenol A (main component of polycarbonate food containers), and perfluorinated chemicals (surfactants).

Her treatment is the same in the chapter devoted to each of these classes of chemical: a saga, that gets repetitive, of the attempt by scientists to publicize alarming, even scandalous results about the risks of a chemical material, and the heavy-handed lobbying effort by manufacturers to discredit them and persuade regulators that "Nothing is wrong; just trust us." Amazingly, regulators in the US do so with numbing regularity.

There is a ray of hope in Europe, which two years ago legislated REACH (Registration, Evaluation, Authorization and restriction of CHemical substances). Other areas of the developed world are taking their cue from REACH, including Canada. The U.S. is suddenly the lagging black sheep! I wonder if even shame can reach the shameless at this point. Because the problem is, carrying out these regulations will make the prices of many things go up.

Let's take a quick look at two toxins we all carry. The average Western person has a "body burden" of about 20 parts per trillion (ppT) of a perfluorinated chemical called PFOS. It is found in the older version of ScotchGuard. This stuff has the chemical formula C₈HF₁₇O₃S, and a molar mass of 500 (keep this number in mind). What does 20 ppT mean?

The number of somatic cells in a human body is between 100 trillion and 200 trillion. The average cell's mass is half a nanogram, or 5x10^-10g. The number of nucleons (protons and neutrons) in a gram is just over 6x10²³. Multiply these two, and the number of nucleons in an average human cell is about 3x10¹⁴, or 300 trillion. Thus one ppT of the human cell would be the mass of 300 nucleons. If a substance has a molar mass of 300, and exists in you at a level of one ppT, then on average each cell in the body contains one molecule of that substance. With me so far?

Now we can puzzle out PFOS: 20x300/500 = 12. Every cell in your body contains about twelve molecules of PFOS. That might sound like a lot, but it probably isn't doing much; there are millions of copies of many enzymes in each of your cells.

But let's look at another bad actor that the author doesn't mention: OCDD, the most common dioxin. Dioxins are the most toxic small molecules known. According to the Third National Report mentioned above, the amount of OCDD in the fat cells ("lipids") of Americans ranges from 1,000 to 1,600 ppT, or 1-1.6 parts per billion (ppB). OCDD has a molar mass of 460, so there are 655 molecules per fat cell, though many fewer in other kinds of cells.

I realize that even 650 molecules of a dioxin isn't really very much, but numbers like that are a tad uncomfortable. Though I work in the chemical field, I am all for my company and others finding alternatives for the worst chemicals in use today, alternatives that are less risky. What will drive up the cost is not the work to find the alternatives, but the work to test them. That's where we need national backing for REACH-type regulations in America.

In my indexing I use the term "polemic". A polemic is not necessarily bad; Silent Spring is a polemic also. Polemic language is intended to wake people up and stir them to action. The Body Toxic can do so, and I hope it does.