Colourful Compound Interest

I discovered Andy Brunning’s Compound Interest last year and got absolutely hooked on it – and I don’t even teach chemistry! If, perchance, you do teach chemistry and don’t yet know what CI is all about, then you probably should check it out. (And if you want to use the material in the classroom, you can download the high-resolution PDF files.) The topics range from general chemistry to material science, chemical warfare and everyday compounds. You’ve got answers to many questions you always wanted to ask but never had time to find out for yourself, like, “is it worth (not) to refrigerate tomatoes?”. The Undeserved Reputations section is a perfect antidote to the “oh my God, our food is still full of chemicals” stream of rubbish published by your Facebook friends.

Here are ten the top ten some of my CI favourites.

Metal Ion Flame Test Colours Chart

1. This is how (I’d like to think) I’ve got interested in chemistry. We used to have a gas hob in our kitchen. I loved the fact that the flame was blue. One day, my brother told me that you can make the flame bright orangey-yellow if you sprinkle it with table salt or bicarbonate of soda. “Why?”, I asked. “Sodium”, was the answer. Unsatisfactory as it was, it stayed in my memory. Yes, chemistry won’t be of any interest to me if not for flame and colours.



Colours of Transition Metal Ions in Aqueous Solution

2. When they are not busy burning or, better still, exploding stuff, your archetypal chemists are often imagined (and therefore portrayed; or is it the other way round?) as hiding behind the test tubes filled with colourful solutions. Which is just as well. The test tubes filled with colourless solutions would be really boring.



What Causes the Colour of Gemstones?

3. Who didn’t dream of finding a treasure, that is, a pirate’s chest filled with gold and jewels? Wait. I still dream of that. I remember how surprised I was when, back in elementary school, I read in some book that ruby and sapphire are basically the same mineral corundum, the only difference is in a type of impurity. Well it’s quite an important difference then. Without impurities, most gemstones would be colourless.



The Chemistry of The Colours of Blood

4. My interest in bioinorganic chemistry (even though at the time I didn’t know at it was called that) was also awakened in school, when I learned that some animals have blue blood. I also discovered that, contrary to what anatomy textbooks show, veins do not carry blue blood in humans. I am not sure if I was relieved or disappointed. Later, already in the university, I read about a Soviet-developed fluorocarbon-based blood substitute nicknamed “Blue Blood”. Fascinating stuff.



The Chemicals Behind the Colours of Autumn Leaves

5. I remember, as a child, reading, or rather browsing, an illustrated book about plants (translated from English), with many beautiful colour photographs. “This apple is yellow because of anthocyanin”. Next page: “This apple is yellow because of carotene”. Next page: “This apple is green because of chlorophyll”. The realisation dawned that, apple-wise, being green is not only necessary but sometimes sufficient.

   But what about leaves? When autumn comes, chlorophyll starts to break down and we get to see other pigments in them. Apart from caroteinoids and flavonoids, there are also coloured chlorophyll degradation products, termed “rusty pigments”.



The Chemistry of Stain Removal

6. Sometimes, however, we want to get rid of all these beautiful colours. The infographic shows the chemical methods of achieving that, although I am not sure that “enzymatic stains” is a correct name for stains caused by blood or grass (yes, haem and chlorophyll again!).



The Atmospheres of the Solar System

7. Alchemists associated seven metals with seven planets (which included the sun and the moon). At the time, it seemed to be quite reasonable. Now that nobody expects Mercury to be made of mercury (and, for that matter, Pluto to be made of plutonium), precious little is known about composition of these planets. About their atmospheres, we’ve learned a bit more. Hey, isn’t it amazing that Mercury’s atmosphere has by far highest percentage of molecular oxygen (42%) compared to any other atmosphere in Solar system? We still won’t be able to breathe there though, because its atmosphere is way too thin (its surface pressure is less than 10⁻¹⁴ bar).



The Metals in UK Coins

8. Compared to gemstones, coins are so much duller, especially now that we don’t come across either gold or silver coins any longer. Continuing the alchemical tradition, we can say that modern British coins of 20 pence and higher are mostly from Venus (that is, copper), while 1 p, 2 p, 5 p and 10 p coins are mostly from Mars (i.e. iron). Of course, you can find much more metal variety in commemorative coins.



The Metal Reactivity Series

9. In contrast to their salts, aqueous complexes and gemstones, pure metals do not offer a great variety of colours. Copper is red, gold is yellow and caesium is yellowish; the rest are coming in many shades of grey. But their chemical behaviour is wildly different, as this infographics shows. You don’t need a sophisticated lab equipment or fancy reagents, just water and some (diluted) acids. If there’s no reaction whatsoever, you’ve got a precious metal. Easy!



Analytical Chemistry – Infrared (IR) Spectroscopy

10. Did I tell you that my first love, as far as the world of analytical chemistry is concerned, was vibrational spectroscopy? If not, I’m telling you now. I’ve never got to do any experiment worthy of a publication, because if I did, believe me, it would have been awesome. This infographics reminded me of happy days of my studenthood when I knew and cared more about amide bands (bless them) than about money or my future career.

Periodic Videos

It’s been a while since I posted anything on this blog, but now I’m back.

This is a very cool collection of videos, “a lesson about every single element on the periodic table”. Featuring Professor and a really awesome reaction, here’s one about one of my favourite elements. Yes, iron is in my blood! (In yours too.)

Kilogram, pterin, selenium

I really enjoyed the latest issue of Chemistry International. Did you know that pterin is called “pterin” because it was first isolated from butterfly wings, and folic acid is “folic” because it was first found in leafy vegetables (from Latin folium)? I just learned that from Edward Taylor’s illuminating article on Alimta [1].

Next, two papers on kilogram in the “New SI”. Currently, kilogram is defined as a unit of mass equal to mass of the international prototype kilogram (IPK), which is a cylinder made of 90% platinum—10% iridium alloy kept at the International Bureau of Weights and Measures in France. The problem is, IPK is losing mass! But even if it did not, it is still not good that one of SI base units is linked to an artifact rather than to something more fundamental. The chemist in me prefers the definition of kilo based on carbon-12 mass [2] to the one based on Planck constant [3].

Finally, essay by Jan Trofast on discovery of selenium [4]. I didn’t know that Swedes discovered so many elements!

1. Taylor, E.C. (2011) From the wings of butterflies: The discovery and synthesis of Alimta. Chemistry International 33, 4—8.
2. Censullo, A.C., Hill, T.P. and Miller, J. (2011) Part I — From the current “kilogram problem” to a proposed definition. Chemistry International 33, 9—12.
3. Mills, I. (2011) Part II — Explicit-constant definitions for the kilogram and for the mole. Chemistry International 33, 12—15.
4. Trofast, J. (2011) Berzelius’ discovery of selenium. Chemistry International 33, 16—19.

Icosahedrite

In 1982, Dan Shechtman observed unusual diffraction pattern in aluminium—manganese alloy [1, 2]. Almost 30 years later, he was awarded The Nobel Prize in Chemistry 2011 “for the discovery of quasicrystals”.

Earlier this year, the first naturally occurring quasicrystal was described. Icosahedrite Al₆₃Cu₂₄Fe₁₃ is a new mineral found in southeastern Chukhotka, Russia. It is named “for the icosahedral symmetry of its internal atomic structure, as observed in its diffraction pattern” [3].

1. Shechtman, D., Blech, I., Gratias, D. and Cahn, J. (1984) Metallic phase with long-range orientational order and no translational symmetry. Physical Review Letters 53, 1951—1953.
2. Fernholm, A. (2011) Crystals of golden proportions. Nobelprize.org.
3. Bindi, L., Steinhardt, P.J., Yao, N. and Lu, P.J. (2011) Icosahedrite, Al₆₃Cu₂₄Fe₁₃, the first natural quasicrystal. American Mineralogist 96, 928—931.

Sometimes metal just plain rusts

Our stainless steel forks and knives, which in England were literally stainless, even spotless, for years, here on Fuerteventura developed rust stains in a matter of days. What’s the matter?

I found this lovely quote from Brion Toss’s book [1]:

Sometimes metal just plain rusts. Stainless steel rusts more slowly, but tropical climates will get to it in just a few years. Galvanized steel left untended can dissolve in a matter of months.

Well said, but what exactly is wrong with “tropical climates”? High humidity and high temperature, that’s what.

But wait. Humidity in Fuerteventura is not higher than in England, right? We hardly have any rain on this island. But the temperature is definitely higher. As is the case with most chemical reactions, the corrosion rate increases with increasing temperature. Add to this salt air. (Salt acts as a catalyst of rusting.) No wonder cars rust quickly here.

Ah well, we always can use the chopsticks.

1. Toss, B. (1998) The Complete Rigger’s Apprentice: Tools and Techniques for Modern and Traditional Rigging. International Marine/Ragged Mountain Press, Camden, Maine.

Metal instruments

This post was prompted by my recent exercises with trombone. Like many (but not all) brass instruments, trombone is actually made of brass, i.e. alloy of copper and zinc. Thus the English term “brass” is more pertinent than French cuivre or Russian медные (both mean “copper”). Still, it is misleading: saxophones (which are woodwind instruments) are also commonly made of brass. But then, I also heard of all-aluminium double bass which was patented in 1934 under the inconspicuous name “Musical instrument of the viol and violin type”.

Can one distinguish the sound of a silver flute from the sound of a gold flute? This study attempted to answer this question with a scientific experiment. Here’s the experimental setup:

A silver coated, full silver, 9 carat gold, 14 carat gold, 24 carat gold, platinum coated and all-platinum flute was played by 7 professional flutists (members of Viennese orchestras including the Vienna Philharmonic orchestra) in an anechoic chamber.

And the result?

As expected, the most significant assigned expressions for all instruments were the “contradictionary <contradictory?> expressions”: for example, the sound color of each instrument was evaluated as “bright” and simultaneously as “dark” or “full/round” and “thin/sharp”.

Tests with experienced professional flutists and listeners and one model of a flute made by Muramatsu from 7 different materials showed no evidence that the wall material has any appreciable effect on the sound color or dynamic range of the instrument. The common stereotypes used by flutists and flute makers are exposed as “stereotypes”.

So there. It’s a shame that Muramatsu does not make aluminium flutes.

Coloured coins

In contrast to gold-, silver- and copper-coloured coins (whatever metal they are made of), simply “coloured coins” sport the colours not usually associated with coinage metals. Or so I think, because so far I could not find any definitive guide to coloured coins. Wikipedia mentions them in an article on commemorative coins. I got interested in the subject since I discovered that the Sherlock Holmes Silver Coins produced by the New Zealand Mint (apparently, the legal tender of the Cook Islands) are graced by the images of Sherlock Holmes and Doctor Watson from Soviet-era films, such as The Hound of the Baskervilles.



The Tony Clayton’s website contains a very useful list of metals used in coins and medals. In particular, I have learned that niobium is used as coinage metal. In 2003, Münze Österreich pioneered the use of niobium for coin manufacturing, issuing a bimetallic €25 coin. According to this review,

The colouring <of the niobium insert> is made by a so called anodic oxidation of the material. With this treatment, by electrochemical processing a very thin niobium oxide layer is formed under controlled conditions. By refraction of light in the oxide layer so called interference colours are created which gives the colouring of the niobium. Depending on the processing parameters, the thickness of the oxide layer can be very well controlled, and gives the niobium its noble appearance. Depending on the thickness of the layer different colours are producible.

For instance, Latvian bimetallic Coin of Time (struck by Münze Österreich) consists of beautiful blue niobium centre enclosed in an outer silver ring. The obverse of the coin features the heraldic rose and the tiny Gothic script letters ℌ and ℜ standing for Heinrich Rose (1795—1864), discoverer of niobium.

On biological role of titanium

According to WebElements, “titanium has no biological role”. Having recently acquired a titanium (or rather, Ti₆AlV₄ alloy) dental implant, I am not convinced. To be a dental implant sounds like a perfectly valid biological role to me. Apparently, osteoblasts like to attach to titanium surface (more precisely, to titanium dioxide, TiO₂). However, it is not just the material that matters, it is the shape of the material as well. In the recent paper, in vivo bone binding to TiO₂ nanotubes and TiO₂ gritblasted surfaces was investigated. The authors have found that

after four weeks of implantation in rabbit tibias, pull-out testing indicated that TiO₂ nanotubes significantly improved bone bonding strength by as much as nine-fold compared with TiO₂ gritblasted surfaces.

Earlier this year, another study has demonstrated that the fate of human mesenchymal stem cells can be affected solely by the geometry of TiO₂ nanotubes:

Small (≈30-nm diameter) nanotubes promoted adhesion without noticeable differentiation, whereas larger (≈70- to 100-nm diameter) nanotubes elicited a dramatic stem cell elongation (≈10-fold increased), which induced cytoskeletal stress and selective differentiation into osteoblast-like cells...

Teaball

I was given this wonderful Teaball as a present from my colleagues. Except from the wooden handle (the wood is not specified), the rest is 18/10 stainless steel. In case you are not familiar with this nomenclature (as I was until the arrival of the Teaball), "18/10" stands for 18% chromium and 10% nickel. It is a far cry from the other kind of stainless steel teapots you can find in this country — no need to use paper napkin etc.

The Force is strong here

If there is a gizmo I really crave to take control of, this is the one. As The NeoCube (Strong Force Inc.) website puts it,

The NeoCube is an entertainment device like no other in the world. Composed of 216 individual high-energy (whatever that means) rare-earth magnets, the NeoCube allows you to create and recreate an outrageous number of shapes and patterns... The NeoCube Alpha is perfect for gaming, expression, stress relief, dual hemispherical brain stimulation and much more.

The rare earth metal in question is neodymium, which, according to Wikipedia, is not that rare at all. Which is a good news for all of us needing affordable dual-hemisphere brain stimulation.

The Darwin coin

Finally, something that has something to do with both Darwin and metals and that you can have in your pocket (quite unlike this bronze sculpture of young Darwin unveiled by Prince Philip today in Cambridge). To celebrate Charles Darwin's 200th birthday (today) and the 150th anniversary of the publication of On the Origin of Species, The Royal Mint issued a special Charles Darwin £2 Coin, although I am yet to see it in my change. (I am not talking here about £2 Silver Proof Coin or £2 Gold Proof Coin, which probably never will be in circulation.)

Metal snow, anyone?

It was snowing heavily yesterday, at least by English standards. Can I find something related to both snow and metal on the web? The googling for “metal snow” does not bring that many interesting results, mostly it’s all about metal tools related to snowy weather. All moderately interesting finds are rather old news. There are couple of papers from 1978 entitled “Plasma cooling by metal snow” (this and this). There, “metal snow” refers to the metal dust “liberated” from the walls of Tokamaks as a result of surface cracking. Another old news item concerns the heavy metal snow discovered on Venusian mountain tops back in 1995. According to Laura Schaefer and Bruce Fegley from Washington University in St. Louis (2004), this “snow” consists of compounds such as galena (lead sulfide), bismuthite (bismuth sulfide), and/or lead-bismuth sulfosalts. The most recent find (2008) is a photo promisingly titled Metal Snow Girl which does not show any snow either, but a snowman-like figure made of metal balls.

Definitions of heavy metal

Anyone who wants to use the term “heavy metal” for any biological or chemical purpose, should consult this publication in Pure and Applied Chemistry first. It has great collection of useless definitions of this term and a conclusion:

The term “heavy metal” has never been defined by any authoritative body such as IUPAC. Over the 60 years or so in which it has been used in chemistry, it has been given such a wide range of meanings by different authors that it is effectively meaningless.

According to yet another definition (not included in the above paper),

Heavy metal is the 666^th element in the periodic table of mixology. Heavy metal is the heaviest of the metals, even heavier than rocks. It was discovered in 1903 by the German physicist Satan although it was not until the industrial revolution of the 1970’s that it became important as the primary ingredient in the manufacture of Lead Zeppelins.