The long awaited and overhyped……….Aluminium!
Aluminium was glamorous once. She had a shiny and glittering past that has dulled with the passage of time to become ordinary and everyday. Aluminium metal has a very high reflectance (only outperformed in the visible region of the spectrum by tin and silver) and it forms the silvery reflective surface under glass mirrors. Mirrors made of pure aluminium would be less successful as the surface reacts with oxygen in the air to form a this, dull oxide layer. It can retain its silvery appearance when its a fine powder which gives it a use in silver paints and even decorative silver cake balls. Worry not, the cake balls are edible and even a whole tub of these would not come close to a dangerous dose of aluminium because it forms such a thin coating.
Aluminium has a chequered past. After many centuries of playing hard to get (the ancient Greeks used aluminium salts) aluminium metal was extracted in its pure form in 1825. The long wait for her arrival was because aluminium is quite reactive. She is quick to latch on to others and then gets quite clingy. Extracting the pure metal is therefore difficult and involves a huge amount of effort and energy. Even modern methods involve huge amounts of electricity used in the process of electrolysis of bauxite (aluminium’s most common ore) making recycling much more efficient.
But once the problems of extraction had been overcome Aluminium burst on to the scene like a glittering starlette. In the 19th century aluminium was novel and precious despite being the most abundant metal in the Earth’s crust. Napoleon III let his most honoured guest use aluminium cutlery while everyone else at the party had to make do with gold. The capstone of the Washington monument is a lump of pure aluminium, chosen because, at the time, it was more valuable than silver. The capstone was even put on display at Tiffany’s before being hoisted to the top of the obelisk.
Today aluminium seems bland and uninteresting because we see it everywhere from cars to rockets and window frames to drinks cans. Although it is difficult to extract the metal from its ore the metal itself is very easy to recycle. Aluminium finds such a wide variety of uses because of its resistance to corrosion and low density. The oxide layer formed with atmospheric oxygen forms an effective barrier protecting the metal underneath from further corrosion. The metal is malleable and tends to be quite soft in its pure form meaning it has to be alloyed with other metals to give it strength.
In the main Aluminium is functional and everyday though a bit of glamour still clings to this element in the form of jewels. Rubies and sapphires are just aluminium oxide compounds contaminated with either chromium or iron. The trace elements give the gems their colour but it is aluminium oxide that makes up the bulk of the structure.
But there is one last party trick that Aluminium has up its sleeves – impersonations. Get seven aluminium atoms together and they do a passable impression of germanium. Thirteen aluminium atoms stuck together look for all intents and purposes like chlorine and chemical tests won’t be able to tell the difference. These clusters of atoms are known as “superatoms” but they don’t have a cape or fight crime.
Should you wish to worship at the feet of aluminium you can do so in Piccadilly Circus. That statue that looks like a bronze Eros… is actually an aluminium Anteros. True.
Next time on a Periodic Tale it’s Carbon’s slightly less versatile, but no less interesting, cousin Silicon.
Image by @SciCommStudios
There has been a long and awkward break from A Periodic Tale over the last *mumbles* months. All the best intentions, it was a busy time, a penguin ate my laptop, I couldn’t find a periodic table and other even less believable excuses. *Ahem*. So, a New Year but not a New Year’s resolution (that would be rash and you’d only give us whithering looks if we fail to live up to it and Lord knows we crumble at a whithering look). We are going to resurrect this blog even if we have have to cut open the chest and massage the heart!
Whilst an aluminium post is being carefully crafted we offer you something to kill the time *cough*. Ta da, have a listen to this, it’s all about Ricin.
@RotwangsRobot and @SciCommStudios
Well magnesium is more interesting than I thought. She may be small but she is awesome. Magnesium (Mg) has been known since ancient times but wasn’t isolated as a pure metal until 1831 by Sir Humphrey Davy. She got her name from where she was found in Magnesia (now part of Greece) as one of two black minerals. The minerals were thought to be male and female. The female mineral, which was used to decolourise glass and wasn’t magnetic, unlike her male counterpart, was named Magnes, later changed to Magnesia and even later found to be Magnesium Oxide.
Magnesium is very very talented but occasionally lets her enthusiasm for showing off get out of hand. It isn’t really Magnesium’s fault as she is being egged on by oxygen. Although magnesium is unreactive when you compare it to lithium or sodium it does have a habit of catching fire at fairly low temperatures and then burning at up to 3000 degrees Celsius. Most of us remember burning strips of magnesium ribbon and being impressed with the bright white flame. This intense reaction between magnesium and oxygen has made magnesium an ideal choice for fireworks (magnesium is the sparkly bit of a sparkler) and flares and was once the flash bit of flash photography.
The low density of magnesium metal has made it an ideal choice for use in lightweight alloys. Combined with aluminium it makes super lightweight alloys used in cars and spacecraft. Magnesium is a strong metal comparable to aluminium but is about two thirds the density of aluminium. The use of magnesium in alloys has not been without problems. One racing team’s attempts to lower the weight of their car resulted in an horrific fire at Le Mans which was only made worse by officials pouring water on the flames in the mistaken belief that they were helping. Magnesium-aluminium alloy is still used, safely, is some engine components and for wheels on your car.
Magnesium is one of the few elements that we can taste but her sour flavour and laxative properties make it an unlikely ice-cream flavour. Which leads me to a story about cows and bath salts. In 1618 a farmer was encouraging his herd of cows to drink from a certain well near the English town of Epsom. The cows refused the water and when the farmer tried it for himself he found it tasted sour. On the plus side the farmer also found that the water caused scratches and cuts on his hands to heal quicker. The key component of the water was magnesium sulfate or Epsom Salts.
Magnesium has many important biological functions and we need about 0.3 grams every day to maintain the huge number of processes magnesium is involved with inside our cells. Of the 24 grams of magnesium in you body about 9 of them are inside your cells attached to over 300 different enzymes. Magnesium is essential to all living organisms! Yup, all of them. And do you see magnesium bragging about it?
But that isn’t even the whole story. No. Magnesium hides her, admittedly very bright, light under a bush(el). Specifically in the chlorophyll in the bushel’s leaves. Chlorophyll is perhaps one of the most important chemical compounds on the planet and has magnesium as its heart. Chlorophyll allows plants and algae to absorb energy from light. It gives us pretty much all the energy we use from food to fuel and keeps our planet habitable. Pretty impressive for such a relatively simple molecule and a process humans are still struggling to mimic in the lab.
Next time it’s cake decorations and ancient Greek myths. It’s aluminium (with two i’s).
Image by @SciCommStudios
Fritz Haber is the Jekyll and Hyde of the chemistry world. He was a brilliant chemist and a total bastard. He was also surprisingly stupid at times and occasionally extraordinarily compassionate.
Haber is known to most of us for his work developing a synthesis of ammonia from nitrogen and hydrogen, work that has fed millions as ammonia is used in fertilizers. This work gained him the 1918 Nobel Prize for Chemistry. He also ran a research institute that was held up as an example of how to foster scientific innovation and high quality research. In Nazi Germany when his Jewish colleagues were forced to leave the institute he did his up-most to find jobs for them abroad before handing in his resignation.
Haber was also involved in more eccentric work in the form of ‘gold from seawater’. This was a fruitless attempt to extract gold to fill the German coffers during the economic disaster Germany found itself in after the WWI. The concentration of gold turned out to be around 1,000 times lower than that necessary to make extraction profitable. But most, if not all, scientists pursue avenues of research that with hindsight look ridiculous. Haber’s name in history is assured because of his work on ammonia, the Haber process.
At school I found the Haber process to be the second most boring part of chemistry (after the spectacular dullness that was ‘the blast furnace’). Going back to it many years later when I was tutoring pupils through the chemistry syllabus I thought it was brilliant. Haber’s achievement of bringing together two gases which really aren’t interested in each other and forcing them to react is a fantastic example of some of the drier fundamental principles underlying chemical reactions. Trying to convey my enthusiasm met with a sceptical if not outright terrified response from my students. I tried again in a recent nitrogen blog but maybe it really is boring and I should stop flogging a dead horse.
Ammonia is very useful as a fertiliser and has indirectly fed millions of people over the past 100 years. However, the major industrial use of ammonia in 1914 was for the production of gunpowder. Without Haber’s discovery it has been suggested Germany’s contribution to the First World War would have lasted three months before they ran out of ammunition. In 1918 when Haber was awarded the Nobel Prize for chemistry, to the utter disgust of the British and French, the committee made a careful omission in their citation of Haber’s work on ammonia. Haber, in his Nobel lecture, forgot to mention ammonia’s use in gunpowder or his work on chemical warfare. Did I mention the chemical warfare thing? This is the bit they left out of my chemistry lessons at school. Fritz Haber is also known as the ‘Father of Chemical Warfare’.
Haber lived by his motto “In peace for mankind, in war for the country!” Using his chemical knowledge Haber developed, and personally oversaw, the deployment of chlorine gas intended as a weapon of mass destruction. The first major release was on April 16th 1915 along a 6km stretch of the Western Front at Ypres. 167 tons of chlorine gas were released and the wind carried it towards the British and French trenches. There were 5,000 casualties and 1,000 deaths. Two days later a second release of chlorine under more favourable conditions lead to 10,000 casualties and 4,000 dead. The prevailing wind at Ypres was from the allies trenches toward the Germans which restricted the number of gas attacks the Germans could carry out. Unfortunately it simply gave the allies more time to develop their own chemical weapons and retaliate resulting in a hideous stalemate and mass slaughter on both sides. Haber was proud of his contributions to the war.
Clara, Haber’s wife did not share his enthusiasm for his military successes. Clara was also a chemist and must have been one of the first women to be awarded a PhD though her marriage to Fritz meant her only roles in life were mother and housewife. On the night Haber returned home to celebrate his promotion to Captain (a reward for the success of the gas attacks) Clara shot herself using Haber’s service pistol. Haber slept through the shots because of his use of sleeping tablets and it was their 13 year old son Hermann who found his dying mother. Unable to get permission to stay Haber left home for the Eastern Front the next day.
None of this seems to have put Haber off as he and his team went on to develop chemical agents such as phosgene and mustard gas. Even after the war Haber continued his work in chemical warfare but under the guise of ‘fumigants’ to avoid contravening the treaty of Versailles. His institute is thought to have developed the now notorious ‘Zyklon B’. The final twist in the tale is that Haber was Jewish (he converted to Christianity when he was 25) and was hounded out of Germany by the Nazi’s who also killed several of his relatives in their gas chambers using Haber’s own invention.
I’ve decided I don’t really like neon. All mouth and no trousers as my mum would say.
Neon has one, attention-grabbing party trick and the rest of time its just doing a very bad impression of helium. Even the name neon is dull. Many of the elements in the periodic table are named after their place of birth, or an eminent scientist, or the name describes the element’s character. Neon was named not by its discoverer Sir William Ramsey but by his young son. William Ramsey junior suggested ‘novum’ for new which was amended to neon because of the convention of naming elements in Greek rather than latin. And that is it. No searching around for a name to inspire or illuminate us, just ‘new’.
So what does neon do? Well, not much. It doesn’t react with anything to form any compounds – just like helium but helium didn’t do anything first and stole all the non-glory for itself. It is lighter than air so it will just about float a balloon but not as well as helium. It forms a liquid at -246 degrees Celsius – just between the boiling points of helium and nitrogen but is considerably more expensive and doesn’t do any of the interesting creeping tricks like helium. The expense is due to neon’s rarity on Earth (only one part in every 65,000 by volume in our atmosphere) despite being relatively abundant in the rest of the universe. One slightly exciting application is in helium/neon lasers (affectionately known as HeNe) but even these are run-of-the-mill lasers that no self respecting Bond Villain would look at twice.
So that party trick had better be good. It is of course neon’s use in, wait for it … neon signs! When you pass an electric current through a tube of neon is glows a bright red/orange colour. But guess what! Helium does it too and makes a rather attractive pink colour. In fact all the noble gases glow in this way producing a range of colours. Neon was the gas most commonly used for this type of lighting and has donated its name to all noble gas lights even when neon isn’t involved. Once neon signs were the perfect answer to advertising. The tubes of gas could be moulded into any number of different shapes and the bright light could be seen at a great distance. To some these lights were a sign of modernity but to others the red colour suggested something more seedy and disreputable. Today very few of these lights are used and what might look like a neon sign is often LED lighting.
But wait! Neon has one last very cool trick up its sleeve. The only problem is that you have to travel to Jupiter to see it. Satellite observations of Jupiter discovered that the outer atmosphere of the planet contained a lot less helium and neon than expected, about 90% less. The missing gas was soon found but much but deeper down. Drawn in by gravity towards the centre of the planet the gas comes under intense pressure and, around the liquid metallic hydrogen layer at about a quarter of the way to the centre, it condenses into a liquid. The liquid droplets experience fiction as they fall and if the drops are big enough and if there is enough friction the droplets will glow in the same way as a neon sign. Imagine streaks of brilliant crimson like millions of tiny meteorites against the backdrop of an orange red Jupiter sky – neon rain.
Maybe neon isn’t so boring after all.
Next time we shuffle and groan our way through zombies and salt, its sodium!
Image @TravisHawke and @SciCommStudios
Fluorine could be a troubled and misunderstood teenager or an unsavoury desperate character hell-bent on getting one extra electron to complete its outer shell. This angry and avaricious element will seemingly go to any lengths to get its fix by stealing electrons from any other element in the periodic table. Only two elements, helium and neon, have managed to resist fluorine’s brutal methods of persuasion. Like a true miser nothing can convince fluorine to part with its own electrons. Perhaps its all down to a difficult childhood. It took 74 years of blood, sweat and tears between Andre-Marie Ampere proposing the existence of fluorine and its isolation by Henri Moissan. Its not easy to trap a gas that eats through most containers. Early attempts to isolate the element resulted in the blinding and death of several scientists (now known as the “Fluorine Martyrs”).
Fluorine the element is a noxious pale yellow gas that is rarely used in its pure form however its main use is in uranium enrichment for nuclear reactors – a process developed during the Manhattan Project. Another notorious application is in the compounds chlorofluorocarbons (CFCs) developed by Thomas Midgley (perhaps the most polluting individual to have ever lived). CFC compounds are now largely banned but not before inflicting major damage on the Earth’s protective ozone layer. It is not then very surprising that fluorine has a bad reputation and when it tries to do good people suspect an ulterior motive.
Fluorine must be the source of more conspiracy theories than any other element. Despite having no known biological function fluoride is sometimes added to drinking water for health reasons (fluorine refers to the element F, flouride means an atom of fluorine with a stolen electron F-). Fluoride has been proved to protect teeth from decay. It works by reacting with the enamel in teeth to form a hard mineral called fluorapatite which prevents cavities forming. The flouride has to come in contact with the teeth so the most effective treatment is to brush with fluoridated toothpaste but many countries still add fluoride to drinking water as it still shows an improvement in health. Consequently adding fluoride to drinking water is the cheapest most effective health care programme any government can instigate but you can see why people get paranoid.
A more exotic use of fluorine is as rocket fuel in place of oxygen. Apparently both the Americans and Russians conducted research into fluorine fuel but later abandoned it for reasons that will become obvious. On paper fluorine is a brilliant choice, being very electron greedy makes it very reactive, being reactive means a lot of energy is released very quickly – just the job if you want to launch a rocket.
On the down side fluorine is not the nicest element to work with (see earlier comments on the Fluorine Martyrs). Another problem is the product of a reaction between hydrogen (the other component of the rocket fuel) and fluorine – hydrogen fluoride (HF). HF is a mild acid but with a devious nature. It is absorbed rapidly through skin and eyes and reacts with pretty much everything in its path down to the bone. The fluoride causes nerve damage meaning people often don’t notice they have been burned and making early treatment less common. When HF gets in to the blood it reacts with calcium ions to form insoluble calcium flouride – having lumpy bits in your blood is a bad thing.
But its not all scaremongering and amputations, fluorine compounds can be very stable and very safe. Fluorine containing compounds have given us good things – non-stick pans and extra slippery skis in the form of Teflon, fire retardants and anaesthetics in the form of hydrofluorocarbons and fluorocarbons, but the one that will entertain a chemist for longest is sulphur hexafluoride (SF6). SF6 is a colourless and inert gas that is heavier than air. Balloons of SF6 will sink like a stone and if you inhale the gas it changes your voice to a bass-baritone (the opposite effects to inhaling helium). You can also fill a fish tank with it and float paper boats on what looks like nothing (more fun than it may sound, especially for a nerd). Perhaps I should get out more.
Next time a periodic tale is off to see the bright lights in a big city – its neon!
Images by @SciCommStudios