Posts Tagged ‘elements’

Rocks and Minerals by Ronald Louis BonewitzRocks and Minerals, Ronald Louis Bonewitz (Dorling Kindersley 2012)

When you read a book, you read your own brain. Somehow the chemicals inside your skull turn electrical signals into conscious experience. Colour is one of the most powerful examples: the difference between the red of cinnabar, the yellow of orpiment and the blue of hemimorphite is ultimately a difference in the firing-rate and strength of nerve-signals. But that’s true of the differences between sight and smell, smell and hearing, hearing and touch, and so on. The nerve-signals are essentially the same: it’s the encoding that changes, but the encoding is quantitative, not qualitative. So how do quanta turn into qualia?

This book brings these questions home very strongly, because its images are so powerful. Minerals can be beautiful or ugly, crystalline or formless, dazzling or dull. Yet all those differences, so sharp in the mind, arise from differing arrangements of the same set of subatomic particles. Smooth blue turquoise has the chemical formula CuAl6(PO4)4(OH)8•4H2O; the orange-red crystals of vanadinite have the formula Pb5(VO4)3Cl. Those very different formulas involve different elements, so it’s not surprising that turquoise and vandanite have very different appearances and chemical behaviour.

But all elements are built of three things: protons, neutrons and electrons. On every page of this book you’re just seeing variations on a threme – a theme of three. But “just” isn’t right for the vastness of what’s going on. The differences between minerals are numerical: the three particles are arranged differently and come in different quantities. Of course, there are sub-atomic forces involved too and smaller units at work in the three particles, but the fundaments of matter are far simpler than the shapes, colours and textures that can be produced by mixing those fundaments in varying proportions.

As you’ll see here: variety is the spice of this book. The geologist Ronald Louis Bonewitz discusses basic chemistry, crystallography and collecting techniques, then works his way systematically through the many families of mineral: native elements, sulphides, molybdates, arsenates, and so on, plus organics like coral and amber. Then there’s a shorter section on rocks: igneous, metamorphic and sedimentary, plus meteorites. Each distinct mineral and rock has an individual page with a colour photograph, a formula, a key of its identification features, and a short text discussing its name, chemistry and uses:

Scorodite FeAsO4•2H2O3

A hydrated iron arsenate mineral, scorodite takes its name from the Greek word scorodion, which means “garlic-like” – an allusion to the odour emitted by the arsenic when specimens are heated. Scorodite can vary considerably in colour depending on the light under which it is seen: pale leek green, greyish green, liver brown, pale blue, violet, yellow, pale greyish, or colourless. It may be blue-green in daylight but bluish purple to greyish blue in incandescent light; in transmitted light it may appear colourless to pale shades of green or brown. Crystals are usually dipyramidal, appearing octohedral, and may have a number of modifying faces. They may also be tabular or short prisms. Drusy coatings are common. Scorodite may also be porous and earthy or massive. Scorodite is found in hydrothermal veins, hot spring deposits, and oxidized zones of arsenic-rich ore bodies. Associated minerals may be pharmacosiderite, vivianite (p. 157), adamite (p. 160), and various iron oxides. (“Minerals: Arsenates”, pg. 165)

There’s a lot here to delight the eye, stimulate the mind and twist the tongue, but chemistry always makes me think of consciousness. It’s a fundamental science and it’s been spectacularly successful in both explaining and altering the material world. This book is a triumph of chemistry both as an object and as an exposition.

But chemistry isn’t all-conquering: it’s helpless to explain the mental aspect of the world. My brain is made of the same basic particles as both this book I’m reading and the minerals it’s describing and depicting. But I’m conscious and they’re not. Science has absolutely no idea how to cross the chasm between matter and mind.

This book wasn’t intended to raise that question, but it does for me. And the better it succeeds in its obvious purpose – portraying, describing and explaining matter – the more strongly it knocks on that stubbornly closed metaphysical door.


Read Full Post »

30-Second Elements ed by Eric Scerri30-Second Elements: The 50 Most Significant Elements, Each Explained in Half a Minute, ed. Eric Scerri (Icon 2013)

Pythagoras thought the world was governed by whole numbers and their ratios. He was wrong, but you could still call chemistry a Pythagorean subject. The huge difference between, say, the noble gas neon and the alkali metal sodium is actually based on a tiny difference in protons. Neon has ten, sodium has eleven. That’s why the two of them behave so differently. As Hugh Aldersey-Williams says on page 64: “Neon is so inert that it forms no chemical compounds at all.” But Brian Clegg says this of sodium on page 16:

This soft, silver-tinted alkali metal is known for its reactivity. Drop a small piece into water and it will fizz energetically as it converts to sodium hydroxide and hydrogen, giving off plenty of heat.

The atomic weight of an element, or the number of positively charged protons it has, affects the number of negatively charged electrons it has. Electrons and their arrangement determine how an element reacts with itself and with other elements. So one proton extra can make a huge difference: it can tip the balance between one configuration of electrons and another, between the inertness of neon and extreme reactivity of sodium.

And sodium obviously isn’t something you’d want to put in your mouth. Except that it is. Sodium is essential for life and isn’t dangerous when ingested as part of the compound NaCl, a.k.a. sodium chloride, a.k.a. table salt. The other half of the compound, chlorine, is also dangerous in its free state: when breathed in, it “burns away the lining of the lungs, leaving victims drowning the fluid that oozes out” (pg. 54).

Elsewhere, carbon and oxygen are the opposite: benign or essential for life when they exist as free elements, but potentially deadly in combination as CO, carbon monoxide, or CO2, carbon dioxide. Chemistry is a complicated business, but there is an underlying simplicity in the whole numbers that represent sub-atomic particles: protons, electrons and neutrons.

This simplicity is laid out in the periodic table, which was proposed and perfected by the Russian chemist Dmitri Mendeleev (1834-1907) in the nineteenth century. As explained in the introduction to this book, the table arranges elements in columns and elements in the same column share chemical properties. Neon is in the column of noble gases, on the far right, while sodium is in the column of alkali metals, on the far left. An extra proton turns helium into lithium, neon into sodium, argon into potassium, krypton into rubidium, and so on. A small change in atomic weight translates into a huge change in chemical behaviour.

An extra proton also turns platinum into gold and gold into mercury. But the transitions in behaviour aren’t as sharp in the inner columns of the periodic table: all of those elements are metals, even though mercury is liquid at room temperature. It’s also poisonous and when it was used to “treat animal fur in hat-making”, it inspired “the phrase ‘mad as a hatter’ and the character of the Hatter in Lewis Carroll’s 1865 novel Alice’s Adventures in Wonderland” (pg. 90). The double-page elemental biographies discuss culture as well as chemistry and chemists, but they’re all brief and this is a primer, not a proper scientific text.

And one page of each biography is occupied by an image: 30-Second Elements is a book for the internet age and its short attention spans. But the images are colourful and inventive – a glowing skeleton dancing amid seashells for “Calcium”; diamonds surrounding a cut-away earth for “Carbon”; the Statue of Liberty atop coils of tubing for “Copper” – and they capture the spirit of chemistry, both as a subject and as a phenomenon. Chemistry is rich, exuberant and endlessly fascinating. All its big names and big discoverers are here, from Lavoisier, Mendeleev and Humphrey Davy to William Ramsey, Marie Curie and Glenn Seaborg.

Read Full Post »