How are amber teething necklaces supposed to work?

Do amber beads have medicinal properties?

Amber, as anyone that was paying attention during Jurassic Park will tell you, is fossilised resin from trees that lived at least twenty million years ago (although some scientists have speculated it could be older). It takes the form of clear yellow through to dark brown stones, seemingly warm to the touch, smooth and surprisingly hard. It is certainly beautiful. But does it also have medicinal properties? And if it does, are they risk-free?

In 2016 a one year-old boy was found dead at his daycare centre in Florida. The cause of death was a necklace, which had become tangled and tightened to the point that he was unable to breathe.

Why was he wearing a necklace? Surely everyone knows that babies shouldn’t wear jewellery around their necks where it could so easily cause a terrible tragedy like this? No one needs a necklace, after all – it’s purely a decorative thing. Isn’t it?

Yes. Yes, it is. However, this particular type of jewellery was specifically sold for use by babies. Sold as a product that parents should give their children to wear, despite all the advice from medical professionals. Why? Because this jewellery was made from amber, and that’s supposed to help with teething pains.

Teething is a literal pain.

Anyone whose ever had children will tell you that teeth are basically a non-stop, literal pain from about 4 months onward. Even once your child appears to have a full set, you’re not done. The first lot start falling out somewhere around age five, resulting in teeth that can be wobbly for weeks. And then there are larger molars that come through at the back somewhere around age seven. Teenagers often find themselves suffering through braces and, even when all that’s done, there’s the joy of wisdom teeth still to come.

It’s particularly difficult with babies, who can’t tell you what hurts and who probably have inconsistent sleep habits at the best of times. Twenty sharp teeth poking through swollen gums at different times has to be unpleasant. Who could blame any parent for trying, well, pretty much anything to soothe the discomfort?

Enter amber teething necklaces. They’re sold as a “natural” way to soothe teething pain. They look nice, too, which I’m sure is part of their appeal. A chewed plastic teething ring isn’t the sort of thing to keep in baby’s keepsake box, but a pretty necklace, well, I’m sure many parents have imagined getting that out, running their fingers over the beads and having a sentimental moment years in the future.

Amber is fossilised tree resin.

So-called amber teething necklaces are made from “Baltic amber,” that is, amber from the Baltic region: the largest known deposit of amber. It is found in other geographical locations, but it seems that the conditions – and tree species – were just right in the Baltic region to produce large deposits.

Chemically, it’s also known as succinite, and its structure is complicated. It’s what chemists would call a supramolecule: a complex of two or more (often large) molecules that aren’t covalently bonded. There are cross-links within its structure, which make it much denser than you might imagine something that started as tree resin to be. Baltic amber, in particular, also contains something else: between 3-8% succinic acid.

Succinic acid is a dicarboxylic acid.

Succinic acid is a much simpler molecule with the IUPAC name of butanedioic acid. It contains two carboxylic acid groups, a group of atoms we’re all familiar with whether we realise it or not – because we’ve all met vinegar, which contains the carboxylic acid also known as ethanoic acid. If you imagine chopping succinic acid right down the middle (and adding a few extra hydrogen atoms), you’d end up with two ethanoic acid molecules.

Succinic acid (the name comes from the Latin, succinum, meaning amber) is produced naturally in the body where it is (or, rather, succinate ions are) an important intermediate in lots of chemical reactions. Exposure-wise it’s generally considered pretty safe at low levels and it’s a permitted food additive, used as an acidity regulator. In European countries, you might see it on labels listed as E363. It also turns up in a number of pharmaceutical products, where it’s used as an excipient – something that helps to stabilise or enhance the action of the main active ingredient. Often, again, it’s there to regulate acidity.

Basically, it’s mostly harmless. And therefore, an ideal candidate for the alternative medicine crowd, who make a number of claims about its properties. I found one site claiming that it could “improve cellular respiration” which… well, if you’ve got problem with cellular respiration, you’re less in need of succinic acid and more in need of a coffin. Supposedly it also relives stress and prevents colds, because doesn’t everything? And, of course, it allegedly relieves teething pains in babies, either thanks to its general soothing effect or because it’s supposed to reduce inflammation, or both.

Purporters claim succinic acid is absorbed through the skin.

The reasoning is usually presented like this: succinic acid is released from the amber when the baby wears the necklace or bracelet and is absorbed through the baby’s skin into their body, where it works its magical, soothing effects.

Now. Hold on, one minute. Whether this is true or not – and getting substances to absorb through skin is far less simple than many people imagine, after all, skin evolved as a barrier – do you really, really, want your baby’s skin exposed to a random quantity of an acidic compound? Succinic acid may be pretty harmless but, as always, the dose makes the poison. Concentrated exposure causes skin and eye irritation. Okay, you might say, it’s unlikely that an amber necklace is going to produce anywhere near the quantities to cause that sort of effect, but if that’s your logic, then how can it also produce enough to pass through skin and have any sort of biological effect on the body?

The answer, perhaps predictably, is that it doesn’t. In a paper published in 2019, a group of scientists actually went to the trouble of powdering Baltic amber beads and dissolving the powder in sulfuric acid to measure how much succinic acid they actually contained. They then compared those results with what happened when undamaged beads from the same batches were submerged in solvents, with the aim of working out how much succinic acid beads might conceivably release into human skin. The answer? They couldn’t measure any. No succinic acid was released into the solvents, at all. None.

Scientists submerged Baltic amber beads in solvents to see how much succinic acid they released.

They concluded that there was “no evidence to suggest that the purported active ingredient succinic acid could be released from the beads into human skin” and also added that they found no evidence to suggest that succinic acid even had anti-inflammatory properties in the first place.

So amber necklaces don’t work to relieve teething pains. They can’t. Of course, there could be a sort of placebo effect – teething pain is very much one of those comes-and-goes things. It’s very easy to make connections that just aren’t there in this kind of situation, and imagine that the baby is more settled because of the necklace, when in fact they might have calmed down over the next few hours anyway. Or maybe they’re just distracted by the pretty beads.

And, fine. If wearing the jewellery was really risk-free, then why not? But as the story at the start of this post proves, it is not. Any kind of string around a baby’s neck can become twisted, interfering with their breathing. Most necklaces claim to have some sort of “emergency release” mechanism so that they come apart when pulled, but this doesn’t always work.

Don’t fall for the marketing.

Ah, goes the argument. But it’s okay, because we only sell bracelets and anklets for babies. They don’t go around the baby’s neck. It’s completely safe!

No. Because I don’t care how carefully you make it: the string or cord could still break (especially if it’s been chewed), leaving loose beads to pose a serious choking hazard. Not to mention get jammed in ears or nostrils. Even if you’re with the baby, watching them, these sorts of accidents can happen frighteningly quickly. Letting a baby sleep with such an item is nothing short of asking for disaster, and no matter how good anyone’s intentions, babies do have a habit of dozing off at odd times. Will you really wake the child up to take off their bracelet? Every time?

In summary, don’t fall for the marketing. Amber necklaces may be pretty, but they’re not suitable for babies. The claims about succinic acid are completely baseless, and the risks are very real.


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The UK’s Unlikely System of Units

The novel Good Omens was first published in 1990. And this is my original copy.

Unless you’ve been asleep for the last few months (if so, are you a snake, by any chance….?) you will have noticed that there’s recently been a very popular television adaptation of the much-loved book by Terry Pratchett and Neil Gaiman: Good Omens.

I have always loved this book, and I love the TV show even more. Obsessed? Erm. Anyway. Can I wring a science-themed post for my blog out of a story about a demon and an angel saving the world from Armageddon? Of course I can.

Here goes. There’s a moment in the second episode of the TV adaptation* when the demon, Crowley, is driving his Bentley very, very fast, and the angel, Aziriphale, says: “You can’t do ninety miles an hour in central London!”

This caused a bit of confusion for some non-British viewers§. Not the idea that you can’t, or at least shouldn’t, drive extremely fast in a built-up area, but rather the fact that Britain is a European country, isn’t it? At least, for the moment. Don’t the Europeans use the metric system? Shouldn’t he have said one hundred and forty-five kilometres per hour?

So you thought Brits used the metric system? Haha.

I mean, okay, we do. Scientists in particular are quite keen on it. But we also use imperial units really quite a lot. And coincidently, this all arose just after the politician Jacob Rees-Mogg issued a style guide to his staff declaring that they must “use imperial measurements” — which at first sounds typically Victorian of Rees-Mogg, but actually… if your aim is to at least try to be consistent, he might, just might, have a point…

Allow me to try to explain.

Firstly, a little clarification: the “metric system” is an internationally-recognised decimalised system of measurement, that is, a system where units are related by powers of ten. I stress this because “metric” and “decimal” do not mean quite the same thing, which is relevant when it comes to money. The metric system takes base measurements — kilograms, metres and so on — and says that all versions of those measurements can only be connected by powers of ten, and must not introduce new conversion factors. So, grams (1000th of a kilogram) and tonnes (1000 kilograms) are both metric, but a pound (0.454 of a kilogram) is not. Scientists know this as the SI system of measurements. Okay? Right. Let’s get on to the amusing cocktail of units the British have to cope with in their every day lives…

Britain loves inches.

Length
The length of small-ish objects is measured in centimetres and millimetres. Sometimes. Except the diameter of pizzas, the sides of photos and photo frames, and the diagonal of laptop screens and televisions — all of which are almost always given in inches. Screws, as in woodscrews, are often given in  fractions of inches. Let’s not get into jewellery, for that way madness lies.

Longer objects are measured in metres and centimetres, except for the height of people, which is almost always quoted in feet and inches. Chippies (that is carpenters, not people that cook fish and chips — keep up) tend to colloquially use feet and inches for planks of wood. For example, “I need a bit of six by nine” — meaning a piece of wood 6 feet long and 9 inches thick.

What do you mean, how do you know which one is 6 and which one is 9? You’d hardly have a 9 ft piece of wood that was only 6 inches thick, would you?

People do sometimes use metres for short walking distances, e.g. “it’s fifty metres to the shops”, however Brits also like to use yards, a yard being 3 feet. But that’s okay, because a yard is close enough to a metre as to make little difference to a casual walking estimate, so they’re pretty interchangeable.

Marathons are measured in miles. Shorter road races use kilometres.

The sorts of distances involved in lengthy travel are always measured in miles. The distance from Oxford the city to Oxford Street in London, for example, is about 55 miles. No British person would ever describe this as 88.5 km. Speed, as we saw in Good Omens, is thusly described in miles per hour (mph). For the record, the speed limit in a built-up area such as Oxford Street would normally be 30 mph, or sometimes (more and more frequently) 20 mph. Crowley was indeed driving ridiculously fast, but then, he has demonic magic to help him avoid both pedestrians and police.

Miles are also used for marathons. However, not for shorter running races, which are often described as “5k” or “10k” meaning, obviously, 5 kilometres or 10 kilometres. The cynics may wonder whether this is because 5 kilometres sounds longer than 3 miles, but I’m sure runners aren’t concerned about such vanities.

Is all of that clear? Okay, let’s move on…

Weight
Weight (physicists: I mean mass, yes, you’re very clever, shhh now) of people is measured in stones and pounds (there are 14 pounds in a stone). Except for babies, which are little and are therefore measured in pounds, because everyone knows a baby ought to weigh somewhere in the region of 7 pounds or so, and if you quote a baby weight in kg, Brits have no idea whether to gasp, coo, or wince sympathetically.

The weight of food is mostly measured in kilograms and grams (or possibly grammes; it’s essentially the same thing) these days, although a lot of people still favour pounds and ounces. This leads to oddities, such cake recipes which call for 225 g of butter (half a pound). There are, by the way, 16 ounces in a pound, because it would be far too easy if it were consistent with the pounds/stones thing, wouldn’t it. Oh, and Brits have quarter pounder beefburgers in restaurants — none of that ‘Royale with cheese‘ business for us, thanks.

Larger weights are mostly quoted in tonnes, because that’s easy, but sometimes we use tons as well, which has the added amusement of sounding exactly the same when you say it out loud. 1 tonne is about 1.1 tons, so it’s not too much of a problem unless you’re planning a really big building project. Very large amounts are sometimes given in hundredweight, which sounds metric, doesn’t it? It’s not. A hundredweight is 50.8 kg, or 112 pounds. Did you think it would be 100? Yes, well, there are reasons.

Once again, let’s not get into jewellery. If we start on carats we’ll be here all day.

Beer, blood and milk are measured in pints.

Volume
Small volumes of liquids tend to be measured in millilitres or (particularly for wine) centilitres. The exceptions are beer, blood and milk — which are given in pints. Wandering into a British pub and asking for half a litre of beer is guaranteed to cause everyone to stop what they’re doing and stare at you. As will asking for pint of blood, for different reasons.

Larger volumes are measured in litres. We’ve mostly given up on gallons, now that all the fuel stations quote their prices in pence per litre because it looks cheaper that way.

Chemists like to be awkward, though, and use cubic centimetres — written cm3 or occasionally cc just for fun — for small volumes of liquids, and dm3 (cubic decimetres) for litres. 1 cm3 is 1 ml and 1 dm3 is 1 litre, so there’s really no reason for any of this other than to confuse students.

Temperature
Temperatures are mostly quoted in Celsius (aka centigrade, well, more-or-less), and most Brits these days have a fairly good feel for that scale. But Fahrenheit still gets rolled out when either a person or the air gets hot. A midsummer’s day might reach ‘100 degrees’ (that is, a little under 38 oC) and someone with a fever might also be described as ‘having a temperature of over a hundred’. Once it gets chillier, however, we’re firmly back to Celsius, because ‘minus five’ sounds a lot more dramatic than 23 oF.

In case you’re wondering, no, I did not choose this particular picture of a thermometer by accident.

In case you thought you were on safe ground here, don’t forget there’s also Kelvin (where 0 oC = 273 K) which is the SI unit of temperature and very popular with physicists. And, if you’re cooking, the mysterious ‘gas mark‘ — which is more-or-less unique the U.K. and which is based on some sort of occult formula. (Gas mark 6 is about 200 oC or 400 38 oF.)

Energy
Energy is measured in Joules. Except when it comes to food, where it’s measured in calories. Actually, kilocalories, but everyone just calls them calories. There’s meant to be a capital C to help tell the difference, but no one ever remembers. This is all fine.

Pressure
Are you sure you want to go here? Okay. FINE.

Tyre pressures are quoted in pounds per square inch, that is, PSI. Most British car owners can probably tell you roughly what their tyre pressures ought to be in PSI, even if (having learned metric at school) they have a somewhat shaky grasp of what either inches or pounds are.

Atmospheric pressures are usually quoted in atmospheres, because everyone knows what that means (sea level is one atmosphere, give or take). Of course, that’s not the SI unit, which is Pascals: 1 atmosphere is 101,325 Pascals, which is a bit unwieldy, so scientists often use bars, where 1 bar is 100,000 Pascals, and thus 1 atmosphere is more-or-less 1 bar, which, for once, is sort of helpful (no, really).

Blood pressure is usually quoted in mmHg

But then there’s also Torr, which arises from the historical practice of using mercury to measure pressure. 760 Torr is 1 atmosphere, while 1 Torr is 133.32 Pascals. Blood pressure, of course, was traditionally measured with a mercury sphygmomanometer, but just in case you thought you were on top of this, 1 Torr is nearly, but not quite, the same as the measurement in that case, which is mmHg, 1 of which is equal to 1.000000142466321 Torr.

Money
British money is decimal (but not metric, for the reasons described back at the start there), but only became so in 1971. If Rees-Mogg has his way I’m sure we’ll be back to pounds, shilling and pence before we know it.

It’s all your fault, isn’t it, Crowley?

In summary….
Since no one in this country is going to give up miles any time soon, if you want to be consistent about units it makes a certain kind of sense to insist on sticking to imperial, I suppose. As much sense as imperial measurements make anyway, which is not much.

You do have to wonder how we ended up with such a confusing mixture of measurements. It’s almost… demonic….


* Page 51 of the original print edition, second line up from the bottom. Obsessed? No idea what you mean.
§ And possibly non-British readers of the book in the 1990s, but Twitter didn’t exist then, so any puzlement went largely unnoticed. It was a quieter time.
would# you? I don’t bloody know. Apparently it’s obvious.
# or, indeed, wood.


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Would you like to listen to the lovely Alasdair Stuart and me natter on about how utterly brilliant Good Omens is, and all the clever little things we spotted in the show for about an hour or so? Of course you would! It’s part of the premium content bucket at the EA Podcasts Patreon. Please do consider supporting Escape Artists podcasts; they produce truly brilliant fiction podcasts on a weekly basis. If you’ve never heard of them (where have you been?) why not subscribe to their free podcasts: Podcastle (fantasy), Pseudopod (horror), Escape Pod (science fiction) and Cast of Wonders (young adult).


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A natural remedy that’s full of chemicals?

Blossoms

The summer holidays are here! A time when parents of small children find themselves exploring every park in their local vicinity, quite probably several times (whilst hoping against hope that it doesn’t rain). On just such a quest myself, I recently visited one particular park that was filled with a gorgeous smell.

What was it? A bit of sniffing around quickly identified this tree. Now, I am not a botanist (or even much of a gardener), so I immediately resorted to the rather wonderful Seek app by iNaturalist, which uses some very clever image recognition software to identify plants and animals (disclaimer: accuracy is not guaranteed — don’t eat anything based on this app!)

Seek told me that this was a lime tree, or a linden (genus Tilia). A bit of cross-referencing (thanks Dad!) suggested that it had identified the tree correctly. It’s not an uncommon plant: you’ll probably come across it yourself if you go looking (or smelling).

The name ‘linden’ was more familiar to me. The wood is soft and easily worked, and is used to make musical instruments because it has good acoustic properties. It’s also used to make wooden blinds and other pieces of furniture because it’s lightweight, stable, and holds stains and finishes well.

Linden blossoms can be used to make tea.

But let’s go back to the flowers and their delicious scent. The tree blooms during July and August in the Northern hemisphere. The flowers are sometimes described as mucilaginous — which is a fabulous word meaning, basically, thick and sticky. More specifically: “containing a polysaccharide substance that is extracted as a viscous or gelatinous solution and used in medicines and adhesives.”

Linden flowers are a ‘natural remedy’ with a list of applications in herbal medicine as long as your arm. They contain lots of different substances. One that comes up a lot is farnesol, which is actually a type of alcohol. Of course, it’s nothing like the alcohol we’re familiar with from drinks, which is the much simpler ethanol — but it’s important to remember that ‘alcohol’ actually refers to a class of compounds (which, in simple terms, contain an -OH group like the one in the image here) and not a single substance.

The chemical structure of farnesol

Farnesol turns up in lots of essential oils, such as citronella, rose and lemon grass. It’s used in perfumes to enhance floral scents. But plants don’t make substances just to please humans (well, it’s complicated…). It acts as a pheromone for several insects. Sometimes this doesn’t work out so well for the insects, as it confuses their mating behaviour and effectively acts as a natural pesticide. On the other hand, it actively encourages others: bumblebees release farnesol when they return to the hive to spur other bees into action. It’s the bee equivalent of shouting, ‘oi! Move it you lot, pollen this way!’

Farnesol acts as a pheromone for bumblebees.

Linden flowers also contain one of my all-time favourite chemicals, benzaldehyde. That’s the one that smells of almonds and isn’t a deadly cyanide salt. Its delicious almondy-ness is the reason it’s used as a flavouring and scent, but it’s also a starting material for loads of different chemicals, for example the dye malachite green, which is used to give a green colour to leather, fabric and paper. A form of this dye called ‘brilliant green‘ is mixed with a second, violet, dye to make ‘Bonney’s blue,’ a disinfectant dye used to mark skin for surgeries. Benzaldehyde is also used to make styrene, which is of course used to make the well-known packing material, polystyrene.

And these are just a couple of the substances found in those yummy-smelling flowers. They also contain arabinogalactans, uronic acid, tannins, rutin, hyperoside, quercitrin, isoquercitrin, astragalin and others. In short, a veritable cocktail of different chemicals.

So next time you smell the scent of a lovely flower, just think about all the amazing chemical substances the plant is making. All natural, of course!


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Let’s change the way we talk about changes

It’s nearly the end of the school year here in the U.K., traditionally a time for reflecting on what’s gone before and planning ahead for the shiny, new September coming in a mere nine weeks (sorry, teachers!). With that in mind, let’s talk about something that comes up early in most chemistry syllabuses, and which bothers me a little more each time I think about it.

Chemical reactions occur when a match burns.

It’s the concept of chemical and physical changes. For those who aren’t familiar, this is the idea that changes we observe happening to matter fall into two, broad categories: chemical changes, where new substances are made, and physical changes, where no new substances are made.

Examples of chemical changes include things like burning a match, cooking an egg, or the reaction between vinegar and baking soda. Physical changes are largely changes of state, such as melting and boiling, but also include changes such as dissolving salt in water, or grinding limestone chips to powder.

So far, so good. Except… then we start to put descriptors on these things. And that’s when the trouble starts.

multiple choice exam questionThe first problem comes with the idea that “chemical changes are irreversible.” This is often taught in early secondary science as a straight-up fact, and is so pervasive that it’s even appeared in multiple choice exam questions, like the one shown here. The student, for the record, was expected to choose option C, “the change is irreversible.”

Except. Argh. I can tell you exactly why the student has opted for D, “the change is reversible,” and it’s not because they haven’t done their revision. Quite the opposite, in fact. No, it’s because this student has learned about weak acids. And in learning about acids, this student met this symbol, ⇌, which literally indicates a reversible chemical reaction.

Yes, that’s right. Not too long after teaching students that chemical reactions are not reversible, we then explicitly teach them that they are. Indeed, this idea of chemical reversibility is such a common one, such an important concept in chemistry, that we even have a symbol for it.

Now, of course, I can explain this. When we say chemical reactions are irreversible, what we mean is “generally irreversible if they’re carried out in an open system.” In other words, when the wood in that match burns out in the open, the carbon dioxide and water vapour that form will escape to the atmosphere, never to return, and it’s impossible to recover the match to its original state.

The problem is that many chemical reactions occur in closed systems, not least a lot of reactions that happen in solution. Hence, the whole acids thing, where we talk about weak acids “partially dissociating” into ions.

Then there’s that entire topic on the Haber process…

Can I be the only one to think that this is rather a lot of nuance to expect teenagers to keep in their head? It’s nothing short of confusing. Should we really be saying one thing in one part of a course, and the literal opposite in another? To be clear, this isn’t even a GCSE vs. A level thing – these ideas appear in the same syllabus.

Melting is a change of state, in this case from (solid) ice to (liquid) water.

All right, okay, let’s move along to the idea that physical changes are reversible. That’s much more straightforward, isn’t it? If I melt some ice, I can re-freeze it again? If I boil some water, I can condense it back into the same volume of liquid… well… I can if I collect all vapour. If I do it in a closed system. The opposite of the condition we imposed on the chemical reactions. Er. Anyway…

We might just about get away with this, if it weren’t for the grinding bit. If physical changes are truly readily reversible, then we ought to be able to take that powder we made from the limestone lumps and make it back into a nice single piece again, right? Right?

See, this is the problem. What this is really all about is entropy, but that’s a fairly tricky concept and one that’s not coming up until A level chemistry.

Okay. Instead of talking about reversible and irreversible, let’s talk about bond-breaking and bond-forming. That’s fine, isn’t it? In chemical changes, bonds are broken and formed (yep) and in physical changes, they aren’t.

Except….

Let’s go back to water for a moment. Water has the formula H2O. It’s made up of molecules where one oxygen atom is chemically bonded to two hydrogen atoms. When we boil water, we don’t break any of those bonds. We don’t form hydrogen and oxygen gas when we boil water; making a hot cup of tea would be a lot more exciting if we did. So we can safely say that boiling water doesn’t involve breaking any bonds, right? We-ell…

Water molecules contain covalent bonds, but the molecules are also joined by (much weaker) hydrogen bonds.

The trouble is that water contains something called hydrogen bonds. We usually do a bit of a fudge here and describe these as “intermolecular forces,” that is, forces of attraction between molecules. This isn’t inaccurate. But the clue is in the name: hydrogen bonds are quite, well, bond-y.

When water boils, hydrogen bonds are disrupted. Although the bonds in individual H2O molecules aren’t broken, the hydrogen bonds are. Which means… bonds are broken. Sort of.

But we’re probably on safe ground if we talk about the formation of new substances. Aren’t we?

Except….

What about dissolving? If I dissolve hydrogen chloride gas, HCl, in water, that’s a physical change, right? I haven’t made anything new? Or… have I? I had molecules with a covalent bond between the hydrogen and the chlorine, and now I have… er… hydrochloric acid (note, that’s a completely different link to the one I used back there), made up of H+ and Cl- ions mingled with water molecules.

So… it’s…. a chemical change? But wait. We could (I don’t recommend it) evaporate all that water away, and we’d have gaseous HCl again. It’s reversible.

Solid iodine is silvery-grey, but iodine vapour is a brilliant violet colour.

Hm. What about the signs that a chemical change is occurring? Surely we’re all right there? Fizzing: that’s a sign of a chemical change. Except… are you sure you know the difference between boiling and fizzing? It’s basically all bubbles, after all. Vapour? But, steam is a vapour, isn’t it? Although, on the other hand, water is a product of several chemical reactions. Colour changes? Check out what happens when you heat a small amount of solid, silvery-grey iodine so that it sublimes (spoiler: there’s a colour change).

Is anyone else really confused by now?

You should be. Your students almost certainly are.

There are, in short, more exceptions to every single one of these rules that there are for that “i before e” thing you learned in English (a rule, incidently, which is particularly galling for scientists who constantly have to deal with weights and heights).

Where do we go from here? I think it’s probably time we asked ourselves why we’re even teaching this concept in the first place. Really, it’s there to get students to think about the difference between changes of state and chemical reactions.

I suspect we need to worry about this rather less than we are: most children are very good at identifying changes of state. They do it instinctively. They only start getting confused about it when we teach them a lot of rules which they then try to apply. I’m pretty sure that’s not the way teaching is supposed to work.

A complicated arrangement of chemical glassware

This could definitely be simpler.

If I had my way, I’d ditch the physical and chemical change labels altogether and, instead, just talk about changes of state and chemical reactions. There is precisely one differentiator between these two, and it is: have we made any new stuff? If the answer is no, it’s a change of state. If the answer is yes, then a chemical reaction has occurred. Job done. (And yes, this would squarely define gaseous hydrogen chloride dissolving in water to form hydrochloric acid as a chemical reaction, and I have no problem at all with that.)

I say we change the way we talk about changes: chemistry has a reputation for being tricky, and this sort of confusing, contradictory thing is part of the reason why.


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How many scientists does it take to discover five elements? More than you might think…

My last post chronicled (see what I did there?) a meandering stroll through all 118 elements in the periodic table. As I read through all the pieces of that thread, I kept wanting to find out more about some of the stories. This is the international year of the periodic table, after all — what better time to go exploring?

But, here’s the thing: 118 is a lot. It took ages even just to collect all the (mostly less than) 280-character tweets together. Elemental stories span the whole of human existence and are endlessly fascinating, but telling all of them in any kind of detail would take whole book (not a small one, either) and would be a project years in the making. So, how about instead having a look at some notable landmarks? A sort of time-lapse version of elemental history and discovery, if you will…

Carbon

The word “carbon” comes from the Latin “carbo”, meaning coal and charcoal.

Let’s begin the story with carbon: fourth most abundant element in the universe and tenth most abundant in the Earth’s crust (give or take). When the Earth first formed, about 4.54 billion years ago, volcanic activity resulted in an atmosphere that was mostly carbon dioxide. The very earliest forms of life evolved to use carbon dioxide through photosynthesis. Carbon-based compounds make up the bulk of all life on this planet today, and carbon is the second most abundant element in the human body (after oxygen).

When we talk about discovering elements, our minds often leap to “who”. But, as we’ll see throughout this journey, that’s never an entirely straightforward question. The word “carbon” comes from the Latin carbo, meaning coal and charcoal. Humans have known about charcoal for many thousands of years — after all, if you can make a fire, it’s not long before you start to wonder if you can do something with this leftover black stuff. We’ll never know who first “discovered” carbon. But we can be sure of one thing: it definitely wasn’t an 18th century European scientist.

Diamond is a form of carbon used by humans for over 6000 years.

Then there are diamonds, although of course it took people a bit longer to understand how diamonds and other forms of carbon were connected. Human use of diamonds may go back further than we imagine, too. There’s evidence that the Chinese used diamonds to grind and polish ceremonia tools as long as 6,000 years ago.

Even the question of who first identified carbon as an element isn’t entirely straightforward. In 1722, René Antoine Ferchault de Réaumur demonstrated that iron was turned into steel by absorbing some substance. In 1772, Lavoisier showed for the first time that diamonds could burn (contrary to a key plot point in a 1998 episode of Columbo).

In 1779, Scheele demonstrated that graphite wasn’t lead, but rather was a form of charcoal that formed aerial acid (today known as carbonic acid) when it was burned and the products dissolved in water. In 1786 Claude Louis Berthollet, Gaspard Monge and C. A. Vandermonde again confirmed that graphite was mostly carbon, and in 1796, Smithson Tennant showed that burning diamond turned limewater milky — the established test for carbon dioxide gas — and argued that diamond and charcoal were  chemically identical.

Even that isn’t quite the end of the story: fullerenes were discovered 1985, and Harry Kroto, Robert Curl, and Richard Smalley were awarded a Nobel Prize for: “The discovery of carbon atoms bound in the form of a ball” in 1996.

Type “who discovered carbon” into a search engine and Lavoisier generally appears, but really? He was just one of many, most of whose names we’ll never know.

Zinc

Brass, an alloy of zinc, has been used for thousands of years.

Now for the other end of the alphabet: zinc. It’s another old one, although not quite as old as carbon. Zinc’s history is inextricably linked with copper, because zinc ores have been used to make brass alloys for thousands of years. Bowls made of alloyed tin, copper and zinc have been discovered which date back to at least 9th Century BCE, and many ornaments have been discovered which are around 2,500 years old.

It’s also been used in medicine for a very long time. Zinc carbonate pills, thought to have been used to treat eye conditions, have been found on a cargo ship wrecked off the Italian coast around 140 BCE, and zinc is mentioned in Indian and Greek medical texts as early as the 1st century CE. Alchemists burned zinc in air in 13th century India and collected the white, woolly tufts that formed. They called it philosopher’s wool, or nix alba (“white snow”). Today, we know the same thing as zinc oxide.

The name zinc, or something like it, was first documented by Paracelsus in the 16th century — who called it “zincum” or “zinken” in his book, Liber Mineralium II. The name might be derived from the German zinke, meaning “tooth-like” — because crystals of tin have a jagged, tooth-like appearance. But it could also suggest “tin-like”, since the German word zinn means tin. It might even be from the Persian word سنگ, “seng”, meaning stone.

These days, zinc is often used as a coating on other metals, to prevent corrosion.

P. M. de Respour formally reported that he had extracted metallic zinc from zinc oxide in 1668, although as I mentioned above, in truth it had been extracted centuries before then. In 1738, William Champion patented a process to extract zinc from calamine (a mixture of zinc oxide and iron oxide) in a vertical retort smelter, and Anton von Swab also distilled zinc from calamine in 1742.

Despite all that, credit for discovery of zinc usually goes to Andreas Marggraf, who’s generally considered the first to recognise zinc as a metal in its own right, in 1746.

Helium

Evidence of helium was first discovered during a solar eclipse.

Ironically for an element which is (controversially) used to fill balloons, helium’s discovery is easier to pin down. In fact, we can name a specific day: August 18, 1868. The astronomer Jules Janssen was studying the chromosphere of the sun during a total solar eclipse in Guntur, India, and found a bright, yellow line with a wavelength of 587.49 nm.

In case you thought this was going to be simple, though, he didn’t recognise the significance of the line immediately, thinking it was caused by sodium. But then, later the same year, Norman Lockyer also observed a yellow line in the solar spectrum — which he concluded was caused by an element in the Sun unknown on Earth. Lockyer and Edward Frankland named the element from the Greek word for the Sun, ἥλιος (helios).

Janssen and Lockyer may have identified helium, but they didn’t find it on Earth. That discovery was first made by Luigi Palmieri, analysing volcanic material from Mount Vesuvius in 1881. And it wasn’t until 1895 that William Ramsay first isolated helium by treating the mineral cleveite (formula UO2) with acid whilst looking for argon.

Mendeleev’s early versions of the periodic table, such as this one from 1871, did not include any of the noble gases (click for image source).

Interestingly, Mendeleev’s 1869 periodic table had no noble gases as there was very little evidence for them at the time. When Ramsay discovered argon, Mendeleev assumed it wasn’t an element because of its unreactivity, and it was several years before he was convinced that any of what we now call the noble gases should be included. As a result, helium didn’t appear in the periodic table until 1902.

Who shall we say discovered helium? The astronomers, who first identified it in our sun? Or the chemists, who managed to collect actual samples on Earth? Is an element truly “discovered” if you can’t prove you had actual atoms of it — even for a brief moment?

Francium

So far you may have noticed that all of these discoveries have been male dominated. This is almost certainly not because women were never involved in science, as there are plenty of records suggesting that women often worked in laboratories in various capacities — it’s just that their male counterparts usually reported the work. As a result the men got the fame, while the women’s stories were, a lot of the time, lost.

Marguerite Perey discovered francium (click for image source).

Of course, the name that jumps to mind at this point is Marie Curie, who famously discovered polonium and radium and had a third element, curium, named in honour of her and her husband’s work. But she’s famous enough. Let’s instead head over to the far left of the periodic table and have a look at francium.

Mendeleev predicted there ought to be an element here, following the trend of the alkali metals. He gave it the placeholder name of eka-caesium, but its existence wasn’t to be confirmed for some seventy years. A number of scientists claimed to have found it, but its discovery is formally recorded as having been made in January 1939 by Marguerite Perey. After all the previous failures, Perey was incredibly meticulous and thorough, carefully eliminating all possibility that the unknown element might be thorium, radium, lead, bismuth, or thallium.

Perey temporarily named the new alkali metal actinium-K (since it’s the result of alpha decay of 227Ac), and proposed the official name of catium (with the symbol Cm), since she believed it to be the most electropositive cation of the elements.

But the symbol Cm was assigned to curium, and Irène Joliot-Curie, one of Perey’s supervisors, argued against the name “catium”, feeling it suggested the element was something to do with cats. Perey then suggested francium, after her home country of France, and this was officially adopted in 1949.

A sample of uraninite containing perhaps 100,000 atoms of francium-223 (click for image source).

Francium was the last element to be discovered in nature. Trace amounts occur in uranium minerals, but it’s incredibly scarce. Its most stable isotope has a half life of just 22 minutes, and bulk francium has never been observed. Famously, there’s at most 30 g of francium in the Earth’s crust at any one time.

Of all the elements I’ve mentioned, this is perhaps the most clear-cut case. Perey deservedly takes the credit for discovering francium. But even then, she wouldn’t have been able to prove so conclusively that the element she found wasn’t something else had it not been for all the false starts that came before. And then there are all the other isotopes of francium, isolated by a myriad of scientists in the subsequent years…

Tennessine

All of which brings us to one of the last elements to be discovered: tennessine (which I jokingly suggested ought to be named octarine back in 2016). As I mentioned above, francium was the last element to be discovered in nature: tessessine doesn’t exist on Earth. It has only ever been created in a laboratory, by firing a calcium beam into a target made of berkelium (Bk) and smashing the two elements together in a process called nuclear fusion.

Element 117, tennessine, was named after Tennessee in the USA.

Like tennessine, berkelium isn’t available on Earth and had to be made in a nuclear reactor at Oak Ridge National Laboratory (ORNL) in Tennessee — the reason for the new element’s name. One of the scientists involved, Clarice E. Phelps, is believed to be the first African American to discover a chemical element in recent history, having worked on the purification of the 249Bk before it was shipped to Russia and used to help discover element 117.

Tennessine’s discovery was officially announced in Dubna in 2010 — the result of a Russian-American collaboration — and the name tennessine was officially adopted in November 2016.

Who discovered it? Well, the lead name on the paper published in Physical Review Letters is Yuri Oganessian (for whom element 118 was named), but have a look at that paper and you’ll see there’s a list of over 30 names, and that doesn’t even include all the other people who worked in the laboratories, making contributions as part of their daily work.

From five to many…

There’s a story behind every element, and it’s almost always one with a varied cast of characters.

As I said at the start, when we talk about discovering elements, our minds often leap to “who” — but they probably shouldn’t. Scientists really can’t work entirely alone: collaboration and communication are vital aspects of science, because without them everyone would have to start from scratch all the time, and humans would never have got beyond “fire, hot”. As Isaac Newton famously said in a letter in 1675: “If I have seen further it is by standing on the shoulders of giants.”

There’s a story behind every element, and it’s almost always one with a varied cast of characters.


This post was written by with the help of Kit Chapman (so, yes: it’s by Kit and Kat!). Kit’s new book, ‘Superheavy: Making and Breaking the Periodic Table‘, will be published by Bloomsbury Sigma on 13th June.


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Element Tales: A Meandering Stroll Around 118 Elements

On 7th Feb this year Mark Lorch, a chemist and science communicator at the University of Hull, had the idea to start an element association game. Could a determined bunch of Twitter chemists find a path through all 118 elements of the periodic table in honour of Periodic Table Day and the International Year of the Periodic Table?

It turned out that they could! #ElementTales started with mendelevium, and meandered — avoiding a few forks — all the way to gadolinium. Some of the links are funny, some are tenuous, and a lot refer to fascinating bits of chemistry trivia.

It seemed a shame not to preserve the final thread somehow. Each of the entries below is headed with a link to the original tweet — just in case you’d like to find, and follow, the thread yourself.

Without further ado, we present to you…

A meandering stroll around 118 elements

@Mark_Lorch
Hey folks! Who’s up for an element association game for in . The rules: I’ll start with an element, you reply with a story/factoid that links it to another element and so on… No repeats!

An atom of Mendelevium, atomic number 101 (from Wikimedia Commons)

@Mark_Lorch
It’s only fitting to start with number 101 Mendelevium

@Sciencenotscary
Mendeleev designed the first periodic table, which contains every other element, including <spins random number generator> #52, tellurium <blink> I swear that was random.

@Stare_at_Air
That feels a bit like cheating! But tellurium was first discovered in gold ore from Zlatna (a Romanian town named after the Slavic term for gold).

@RyeSci
Gold is one of those lovely elements known to the ancients with a symbol accordingly, Au. My favourite of those is Mercury, Hg from Hydrargyrium or liquid silver Hg.

@chronicleflask
Mercury has a v low MP because its electronic config, [Xe] 5d10 6s2, has all full shells — so it doesn’t form the +ve metal ions & delocalised electrons bonding system as other metals. Also quantum. Zn (zinc) has a low MP for the same reason.
(Side note: see this article for more info on mercury’s liquidity https://www.chemistryworld.com/news/relativity-behind-mercurys-liquidity/6297.article)

@allisontau
Zinc is element 30. Zinc rhymes with sink. If your kitchen sink is broken you call a plumber. Plumbers are called plumbers after plumbum, the Latin word for the element lead (Pb), because the Romans used lead to make pipes.

@Mark_Lorch
Lead in Greek is μολυβδος – Molyvdos which gives use the name of element 42, molybdenum.

bacteria@chronicleflask
Molybdenum-containing enzymes are found in bacteria: the simplest and oldest of the living organisms. Living organisms on planet Earth have carbon-based biology. (Time for some non-metals, I thought!)

@Stare_at_Air
This could be taken in so many directions based on carbon‘s chemistry, but I’ll ruin it — carbon reminds me of “Carboniferous”, which sounds like it should have something to do with iron (it doesn’t).

@sciencenotscary
Iron is in the same column of the periodic table as ruthenium, which usually means it should have similar reactivity and chemical behaviour, but it turns out iron is actually completely useless as a catalyst and will not get you a PhD.

@SuperScienceGrl
I’ve had a couple of people mistake my cat’s name, RuPhos, for something to do with ruthenium – it really isn’t, it’s a phosphorus ligand.

@Mark_Lorch
Phosphorus was first extracted from urine by Hennig Brandt in 1669. Later is was discovered that bone is calcium phosphate, which made for a ready supply to feed the match industry.

@David_S_Bristol
Calcium and phosphorous combine in bone along with a substantial amount of magnesium. ~60% of magnesium in the body is in bone. It is essential for a healthy skeleton and reduced magnesium is linked to osteoporosis.

@Stare_at_Air
Magnesium is a key component of Grignard reagents. Grignard shared his Nobel Prize with Sabatier, who in turn received it for his method of hydrogenating organic compounds. Hydrogen.

@drdelusional
Hydrogen, the lightest element, forms the majority of the mass of the Universe. This odorless and tasteless gas combines with Fluorine to result in hydrogen fluoride, a highly reactive acid.
(Side note: corrosive, not (especially) reactive.)

@WildCation
Electronegativity generally increases from left to right across a period, and generally decreases from top to bottom. Fluorine is the most electronegative element on the Pauling electronegativity scale. The LEAST electronegative element is (probably) caesium.

@chronicleflask
Ooh, ooh: Robert Bunsen (he of the burner) and Gustav Kirchhoff discovered two alkali metals, cesium and rubidium, in 1860.

@Stare_at_Air
Rubidium is one of several elements named after a colour (in this case the red lines seen in the emission spectrum), but chromium is associated with so many different colours it’s just named after the Greek word for colour, χρῶμα.

@Mark_Lorch
Amongst the Terracotta warriors were found what appears to be chrome (chromium) plated bronze swords. The alloy was mostly copper and tin, but also contained magnesium, nickel and cobalt.

@sumants
Cobalt is named from ‘kobold’, German for ‘goblin’. This comes from German miners – who were harvesting (cobalt) blue pigments – naming ores ‘goblin ores’ due to the effects of arsenic poisoning when the ores were smelted.

@WildCation
The use of Scheele’s Green, a popular green arsenic-based pigment, caused poisonings in the 19th century from its use in wallpaper, candles, even food. Similarly, in the 1920s, the “Radium Girls” developed cancer from painting watch faces with radium-based pigment.

@Mark_Lorch
Radium was discovered by Marie and Pierre Curie when they extracted it from Uraninite ore. From the same ore they extracted another element which they initially called radium-F. Later Marie renamed if after her home country – Poland. Giving us … Polonium.

@Stare_at_Air
I think the f-block is feeling a bit unloved, so let’s go from the elements that the Curies discovered (Polonium) to the one named after them. Curium.

@ndbrning
Curium is (possibly) the heaviest naturally occurring element (see here: https://www.nature.com/articles/s41557-018-0190-9). The other possible candidate is plutonium.

@Stare_at_Air
Plutonium was indirectly named by a child (the name Pluto for the planet was suggested by an 11-year-old girl). The only other element named by a child is neon, suggested by Ramsay’s son.

@Mark_Lorch
William Ramsay (neon) was also the first person to isolate helium. Prior to this is was known to exist from the spectra of the Sun. Hence the element’s name from Helios… Helium.

@DrMLHarris
Inhaling helium makes your voice squeaky. What happens if you inhale xenon? Researchers at a prestigious US lab decided to find out. Turns out, “heavier than air”=”too heavy for lungs to expel”. The experimenter’s life was saved when he stood on his head.
(Side note: watch what happened when Dr Bunhead of Brainiac tried the same thing.)

@FioraAeterna
Xenon is a really unusual element. In fact, it’s the only pure element that is also a general anesthetic! Yet it’s an unreactive noble gas. Weird, huh? For weird reasons, both Xenon and Argon are now on the anti-doping banned chemicals list.

@Stare_at_Air
People are often surprised to find that the third most abundant gas in the Earth’s atmosphere is Argon. Perhaps similarly surprising is that the third most abundant element in the universe as a whole (at least as far as we know) is oxygen.

@Mark_Lorch
Oxygen is a paramagnetic. If you condense some (it’s a beautiful pale blue liquid) and then place a neodymium magnet above the surface the oxygen jumps up onto the magnet. https://www.youtube.com/watch?v=bQKVt27SUR0&feature=youtu.be&t=91

@sumants
Neodymium was originally mined as a twinned material known as didymium. Carl Auer von Welsbach fractionally distilled didymium to isolate neodymium (new twin) and the other “green twin”, praesodymium.

@Stare_at_Air
“Green twin” in Greek (πράσινος and δίδυμος) is the base for the name of praseodymium — meanwhile “green twig” in Greek (θαλλός) is the base for the name of thallium, after the bright green spectral line used to identify it.

@sumants
Thallium was extremely popular as a poison in the early 20th century, but it’s mostly banned today. As a rat poison, it worked because it inhibited proteins that contained cysteine, an amino acid that contains… Sulphur.

@ndbrning
Sulfur
is responsible for the tarnishing of silver. The black tarnish is silver sulfide, caused by the metal’s reaction with small amounts of hydrogen sulfide in the air.

@Mark_Lorch
To clean your silver spoons put them in hot water with bicarb of soda & aluminium foil. The bicarb removes the aluminium oxide layer. This leaves the aluminium free to react with the silver sulfide, giving aluminium sulfide & clean silver.

@Stare_at_Air
What is still often called “tin foil” is nowadays almost always made from alumin(i)um. But it used to be made exclusively from tin until the early 20th century (first Al foil came around in 1910, but it took a few decades for it to replace Sn foil).

@sciencenotscary
Tin has two allotropes, a metallic one and a powder. It converts to the powder at Russian-winter temperatures. Napoleon’s troops had tin buttons on their jackets, which then wouldn’t close, and they died of exposure. Russia is the home of Dubna. Dubnium.

@ndbrning
One of the originally proposed names for Dubnium was Nielsbohrium, after Danish nuclear physicist Niels Bohr. Though this proposal wasn’t accepted, Bohr did eventually get an element named after him: element 107, bohrium.

@sumants
One of the two groups to have claimed discovery of bohrium in 1976 was led by Soviet scientist Yuri Oganessian, in whose honour we now have… Oganesson.

@robcarrphoto
Only 5 to 6 atoms of Oganesson have ever been detected. Originally thought to be a gas, computational chemistry revealed it would be a solid due to relativistic effects. Special & General Relativity were discovered by Albert Einstein, for whom Einsteinium was named.

@Stare_at_Air
Einstein (Einsteinium) famously developed his theory of relativity while working at the patent office. The first element to be patented was Americium.

@Mark_Lorch
Americium is created by bombarding uranium or plutonium with neutrons. It was first made by Seaborg (from Berkeley) in 1944 as part of the Manhattan project. Soooo many ways to go from here, but I’m going with… Seaborgium.

@Stare_at_Air
Shortly after the ACS announced 106 to be Sg (Seaborgium) in 1994, resolved not to allow names based on living people. Until it gave way about a year later, the IUPAC name for 106 was rutherfordium. In 1997, this name was instead assigned to element 104… Rutherfordium.

@chronicleflask
Rutherfordium was named after Ernest Rutherford, prob. most famous for the Rutherford atomic model developed after Geiger & Marsden’s gold foil expt. But he also carried out research into nuclear reaction bet. nitrogen & alpha particles.

@sciencenotscary
Nitrogen is usually thought of as being mostly inert an unreactive, until you make it an azide. Sodium azide is what inflates your car’s airbag in time to stop your head smacking the steering wheel.

@Mark_Lorch
After my grandpa died I helped clear his flat, over the years he had stashed various chemicals including 1/2kg of Na (sodium), KCN & conc HCl. To this day I shudder to think what might have been if I hadn’t been there to stop my family chucking it all down the sink. Chlorine.
(Side note: read more about that story here http://www.chemistry-blog.com/2013/04/18/chemical-nostalgia-my-grandfathers-lethal-legacy/)

@robcarrphoto
In organic chemistry lab, we used a lot of HCl (chlorine) of organic reactions, making salts, etc. But when I think of the Chemistry building, I think of bromine. The building smelled like bromine. The set of Beilstein books smelled like bromine.

@Mark_Lorch
Two of the elements stink. Bromine means “stench” and osmium means “smells”.

@ndbrning
Osmium is used in an alloy to make the tips of fountain pens hard and wear-resistant. In the past, iridium was used for this purpose, and sometimes the tipping material is still referred to as ‘iridium’ despite the element’s absence.

@Stare_at_Air
Not only was iridium discovered in the residue from trying to dissolve (impure) platinum, but Pt-Ir alloys are very useful, being both hard and chemically stable. The prototype kilogram is made of Pt-Ir, though a new definition of the kg comes in in May.

@sumants
The Pt-Ir (platinum) alloy was also used to make the prototype meter bar, which was replaced by a measure based on an electron transition within a Kr-86 atom. Krypton.

@sumants
While we’re going on about defining lengths, the Kr-86 (krypton) standard also redefined the ångström as 0.1nm, making obsolete the previous reference based on the spectral line of… cadmium.

@ndbrning
Cadmium is used in nickel-cadmium (Ni-Cd) rechargeable AA batteries. Due to cadmium’s toxicity, their sale has been banned in the EU for most purposes since 2006. They’ve been supplanted by another type of nickel-based battery, nickel metal hydride (NiMH).

@drdelusional
Breithauptite or NiSb (nickel) is a pale copper red colored mineral named after Johann Friedrich August Breithaupt, a Saxon Mineralogist. Antimony.

@chronicleflask
Antimony compounds have been powdered for use in medicine and cosmetics for thousands of years, often known by the Arabic name, kohl. Titanium dioxide is another common additive in makeup and sunscreens.

@Mark_Lorch
Titanium
 causes no immune response, making it an ideal material for implants. However it does slowly corrode in the body. A ceramic made of zirconia (zirconium dioxide) doesn’t suffer from this problem and is now commonly used for dental implants. Zirconium.

@drdelusional
Zirconium alloys are mainly used in nuclear reactors, however these alloys should not contain Hafnium.
(Side note: see this article for more info as to why http://www.iloencyclopaedia.org/part-ix-21851/metals-chemical-properties-and-toxicity/63/zirconium-and-hafnium)

@Stare_at_Air
Hafnium is one of two elements whose name is based on the Latin form of a Scandinavian capital — Hafnia is Copenhagen, while Holmia is Stockholm. Holmium.

@sumants
While working with erbia (grounds for a whole fascinating fork!), Per Cleve isolated two oxides, one which he called holmia (holmium oxide), and the other, thulia, which was identified as thulium oxide. Thulium.

@sumants
Thulium is commonly found in a mineral known as gadolinite, which is named after Johan Gadolin. While it doesn’t have much gadolinium in it, Gadolin wrongly thought a white metal he found in it was aluminium, and not… Beryllium.

@ndbrning
Beryllium is found in the mineral beryl, which emerald and aquamarine are precious forms of. One of the rarest varieties, red beryl, gets its colour from the presence of small amounts of manganese.

@chronicleflask
Manganese is used in REDOX titrations; the colour change from VII (dark purple) to II (pale pink) is very obvious. It’s commonly used to determine the amount of iron present. Another species that turns up in REDOX titrations is iodine/iodide.

@sciencenotscary
Iodine can occur in the form HIO4, periodic acid, which looks like the word for the table we’re talking about but is actually per-iodic. A metallic compound with a very similar electronic structure is perhenate, based on rhenium.

@ndbrning
Rhenium was (possibly) first discovered by Masataka Ogawa in 1908, though he thought he’d discovered element 43, technetium (which wasn’t actually discovered until 1937).

@sciencenotscary
One of only two cis-uranic elements with no stable isotopes, it (technetium) had to be synthesised to be discovered (hence the name). The other one is protactinium.

@ndbrning
The first long-lived isotope of protactinium was discovered by Otto Hahn and Lise Meitner in 1917. 80 years later, in 1997, Meitner became one of only 16 scientists to have an element named after them… Meitnerium.

@MrVanOosterhout
Meitnerium was first produced by German nuclear researchers in 1982, who bombarded a bismuth sample with iron ions. A week of bombardment produced a single meitnerium ion, which lasted all of five milliseconds before decaying.

@chronicleflask
The name bismuth dates from around the 1660s, and it’s unclear where it came from, but maybe from Old High German hwiz (“white”). Like water, liquid bismuth is denser than solid, a characteristic it also shares with the element germanium.

@Stare_at_Air
The name germanium proved controversial, sounding like geranium. Jokingly, angularium was proposed, hiding a translated form of the discoverer’s name (Winkler). Lecoq denied doing something similar when naming gallium (Gaul, but also gallus = rooster).

@drdelusional
Gallium is a low melting solid (melting point ~30°C) and it combines with selenium to form Gallium Selenide which finds applications in nonlinear optics.

@sumants
Selenium was identified by Berzelius and Gahn from pyrite found in the Falun mine in Sweden, which is one of the world’s largest repositories of Copper.

@Mark_Lorch
Eight elements were first isolated from rocks quarried in a the small village of Ytterby in Sweden (same country as copper mine). Four of those elements are named in tribute to the village (ytterbium, erbium, terbium, yttrium)… Ytterbium.

@Stare_at_Air
Near the Ytterby (ytterbium) mine is this sign, discussing Gadolin’s work and the elements found there. It talks about a “tung, svart sprängsten” (in this case the black, heavy gadolinite), but it just reminded me of the origin of the name tungsten!

@drdelusional
A compound of Tungsten, Potassium tungsten oxide, is used in solar energy and water treatment applications… Potassium.

@DrMLHarris
Potassium comes in both fermionic and bosonic isotopes, making it ideal for the study of both Bose-Einstein condensation and cold Fermi gases. Lithium also has this property.

@DrMLHarris
The first molecular Bose-Einstein condensate was created in 2003 by pairing up atoms of fermionic lithium-6 (lithium) to make bosonic Li2 molecules. Fermions are, of course, named after the physicist Enrico Fermi, who also has an element named after him... Fermium.

@sumants
Fermium was discovered in the fallout from a nuclear test, as was einsteinium when some filter papers were exposed to the same fallout. The work happened at the University of California, Berkeley, after which place we have… Berkelium.

@sumants
Berkelium is now synthesized mainly in the Oak Ridge National Laboratory in Tennessee, after which state, we have Element 117… Tennessine.

@DrMLHarris
Tennessine itself was synthesized at the Joint Institute for Nuclear Research in Dubna, Russia. The many contributions of this institute to the Periodic Table were recognized in the name of Element 115… Moscovium.

@sumants
Moscovium naturally underwent alpha emission and created… Nihonium.

DrMLHarris
Nihonium was named after the country where it was discovered, Japan. The discoverers expressed hope that this honour would help the country’s trust in science recover after the meltdown of the reactor at Fukushima, which uses uranium as fuel.

@sumants
Uranium, of course, is named after the planet Uranus. It probably makes sense, then, that its neighbour would be named after the planet’s neighbour, Neptune… Neptunium.

@Stare_at_Air
Despite many previous false claims of having produced element 93, including by Fermi, neptunium was first produced by McMillan and Abelson, at Berkeley Lab (yes, Berkeley again, of course), based in the state of California… Californium.

@sumants
Californium was first synthesized at the Lawrence Berkeley NL, which is named after Ernest Lawrence, after whom we have… Lawrencium.

@Mark_Lorch
Lawrencium is the final member of the actinides. Although it is arguably a member of group 3 along with scandium, yttrium, and lutetium… Scandium.

@sumants
When Mendeleev placed scandium in his periodic table, he had previously predicted its existence, which Per Cleve eventually confirmed. He named it eka-boron, since it would have been similar in its properties to… Boron.

@sumants
Borosil is a brand name that makes borosilicate glass, which is made from a compound oxide of boron and… Silicon.

@DrMLHarris
The A3B group of compounds (A=transition metal, B=anything) wasn’t considered particularly interesting until vanadium silicide, V3Si, (silicon) was found to act as a superconductor at 17K – one of the first Type II superconductors to be discovered… Vanadium.

@chronicleflask
Vanadium is famous for its many colours and oxidation states. The ability to readily change oxidation state makes it a good catalyst, notably for the contact process, used to make sulfuric acid. Another element which is used in catalysis is rhodium.

@ndbrning
Rhodium is used in catalytic converters in cars to remove nitrogen oxides, carbon monoxide, and unburnt hydrocarbons. Other metals used as catalysts in these converters are platinum and palladium.

@DrMLHarris
In 1989 Pons & Fleischmann claimed to have observed cold fusion via electrolysis of heavy water on a palladium electrode. That was false, but controlled hot fusion in tokamaks is real. Tokamaks use superconducting wire made from an alloy of tin and… Niobium.

@sumants
Niobium is named after Niobe from Greek mythology, and unsurprisingly, the next element one period down is named for her father, Tantalus… Tantalum.

@Mark_Lorch
Tantalum is one of those elements that was discovered in the rocks of Ytterby. Which gives its name to 4 elements, including … erbium.

@sumants
Along with ytterbium and erbium, the same rocks near Ytterby also yielded… terbium.

@DrMLHarris
Today’s main source of Terbium, however, is a mineral called bastnasite, which is named after yet another Swedish mine, Bastnas. This mineral is also a major source of… Cerium.

@Stare_at_Air
Cerium is named after Ceres, a dwarf planet hypothesised to contain an ocean of liquid water. A similar ocean is thought to exist inside Europa, the Jovian moon, named after the figure in Greek mythology. Also named after it is Europe… Europium.

@sumants
Europium(III) oxide is used to activate yttrium phosphors, mostly to create red on television and computer screens. Yttrium is also one of the elements to come out of the Ytterby mine.

@sciencenotscary
Like Yttrium, Indium is also used in screens because of its importance as a component of the semiconductor indium tin oxide.

@ndbrning
Radioactive indium ions have been investigated by researchers for their potential use in radiopharmaceuticals for diagnosis and treatment of tumours. Radioactive actinium ions have been investigated for the same purpose.

@mrfarabaugh
Actinium assumes oxidation state +3 in nearly all its chemical compounds. The Ac(III) ion has an electron configuration that is isoelectronic with Radon.

@sciencenotscary
Radon, being inherently radioactive, is a nuisance background for sensitive particle detectors. Another nuisance is thorium.

@Stare_at_Air
Thorium is named after Thor, the Norse god of thunder, on whom characters in many a comic have been based over the years. Prometheus, a Titan from Greek mythology, has also made an appearance in several comics and gives his name to element 61… Promethium.

@Mark_Lorch
Henry Moseley showed that atomic numbers corresponded to a physical property of the elements. Using this he found that some atomic numbers had no known elements: the gaps were 43, 61 (promethium), 72, 75, 85 (astatine), and 87.

@Stare_at_Air
All the group 17 elements up to and including astatine (“unstable”) are named after their properties (Ts ruined it), but many elements in the rest of the table are too. We still have two of these left — one of them is “hard to get” (though stable)… Dysprosium.

@Mark_Lorch
(Dysprosium) And the other is Barium which is derived from mineral baryte in which it is found. This in turn comes from the Greek βαρύς (barys) meaning heavy.

@DrMLHarris
Even heavier than barium, and much harder to obtain due to its half-life of just 22 minutes, the next element has never been observed in bulk, though like the other alkalis it has been laser cooled and trapped. Step up… Francium.

@Mark_Lorch
Marguerite Catherine Perey (a student of Marie Curie) discovered Francium and named if after her home country. France gets another hat tip in the table in the form of Lutecium which is named from the latin for Paris.

@DrMLHarris
(Lutecium) Another Paris-based discoverer was Paul-Émile Lecoq de Boisbaudran. He discovered three elements. Two of them, gallium and dysprosium, have been done already, but the third was… Samarium.

@DrMLHarris
De Boisbaudran is credited as Samarium‘s discoverer, but a different French chemist, Eugène-Anatole Demarçay, actually isolated the pure metal. Demarçay destroyed his eyesight in a chemical explosion. The godfather of explosive chemistry is Alfred Nobel… Nobelium.

@Stare_at_Air
Nobel (Nobelium) may have set up the Nobel prize because he was worried about being remembered for his contribution to developing more effective weapons. Georgy Flyorov also played a role in weapons research, as he encouraged Stalin to start an atomic bomb project… Flerovium.

@DrMLHarris
(Flerovium) The most dangerous isotope in nuclear fallout, the hazards of which helped to persuade the US, UK and Soviet Union to ban above-ground weapons tests, is strontium-90, which is taken up in the bones… Strontium.

@sumants
One of the popular electrode materials in solid oxide fuel cells is LSM, which is a perovskite (ABO3) in which B positions have Mn, and A slots are occupied by strontium and… Lanthanum.

@DrMLHarris
The name “lanthanum” derives from the Ancient Greek for “to lie hidden.” X-rays are also good at revealing hidden things, from broken bones to chemical structures to black holes. They were discovered by Wilhelm Roentgen, who is honoured with Element 111… Roentgenium.

@sumants
Roentgenium was first created at the Helmholtz Centre for Heavy Ion Research in Darmstadt, from which we have… Darmstadtium.

@sumants
Several elements have been synthesized/discovered at the Helmholtz Center, including meitnerium, roentgenium, darmstadtium, bohrium, and… Hassium.

@sumants
(Hassium) I left out one more element synthesized at the Helmholtz Center: Copernicium.

@sumants
(Copernicium) The Helmholtz Center also helped confirm Element 116, which had been created partly in Dubna, and partly at the Lawrence Livermore NL, after which it was named: Livermorium.

@DrMLHarris
(Livermorium) All of these reactors used to discover ultra-heavy elements require good shielding against radioactivity. Because of its high neutron cross section, one of the elements used in shielding is… Gadolinium.

@Mark_Lorch
YEH!!! 👏 🥳 🎉 That was great fun! Thanks for playing! I honestly wondered if that was even doable!
#ElementTales

Periodic Table by Andy Brunning of Compound Interest (click for more)


Special thanks to Andrea Chlebikova (@Stare_at_Air) for keeping track of which elements had and hadn’t been covered as we went along.

You can also read an article about this project, published in Physics World, by Margaret Harris (@DrMLHarris).

Further thanks to: Mark Lorch, Andrea Chlebikova, Andy Brunning, Steve Maguire, Michael Farabaugh, Margaret Harris and Sumant Srivathsan. Follow the Twitter handle links to find these lovely people and give them a follow.

Let’s speed up the rate at which we recognise our female chemists

A little while back now I was researching my post on water when I came across a scientist which I hadn’t heard of before. And that was odd, because this person was one of the first to propose the idea of catalysis, which is a pretty important concept in chemistry, in fact, in science in general. Surely the name should be at least a bit familiar. Shouldn’t it?

And yet it wasn’t, and the more I read, the more surprised I was. Not only was this person clearly a brilliant thinker, they were also remarkably prescient.

Elizabeth Fulhame’s book was first published in 1794 (image by the Science History Institute, Public Domain)

So who was it? Her name was Elizabeth Fulhame, and we know very little about her, all things considered. Look her up and you won’t find any portraits, or even her exact dates of birth and death, despite the fact that her book, An Essay on
Combustion,
was published in more than one country and she, a Scottish woman, was made an honorary member of the Philadelphia Chemical Society in 1810 — remarkable achievements for the time.

As well as describing catalytic reactions for the first time, that book — first published in 1794 and surprisingly still available today — also contains a preface which includes the following:

But censure is perhaps inevitable; for some are so ignorant,
that they grow sullen and silent, and are chilled with horror
at the sight of any thing, that bears the semblance of learning,
in whatever shape it may appear; and should the spectre
appear in the shape of a woman, the pangs, which they suffer,
are truly dismal.

Obviously women are interested in physics. And also, apparently, in staring wistfully into open vacuum chambers whilst wearing unnecessary PPE (stock photos are great, aren’t they?)

Fulhame clearly did not suffer fools gladly (I think I would’ve liked her), and had also run across a number of people who felt that women were not capable of studying the sciences.

Tragically, 225 years later, this attitude still has not entirely gone away. Witness, for example, the recent article featuring an interview with Alessandro Strumia, in which he claimed that women simply don’t like physics. There were naturally a number of excellent rebuttals to this ludicrous claim, not least a brilliant annotated version of the article by Shannon Palus — which I recommend because, firstly, not behind a paywall and secondly, very funny.

Unfortunately, despite the acclaim she received at the time, Fulhame was later largely forgotten. One scientist who often gets the credit for “discovering” catalysis is Berzelius. There is no doubt that he was a remarkable chemist (you have him to thank for chemical notation, for starters), but he was a mere 15 years old when Fulhame published her book.

The RSC’s Breaking the Barriers report was published in 2018

In November last year, the Royal Society of Chemistry (RSC) launched its ‘Breaking the Barriers’ report, outlining issues surrounding women’s retention and progression in academia. As part of this project, they commissioned an interview with Professor Marina Resmini, Head of the Chemistry Department at Queen Mary University of London.

She pointed out that today there is an almost an equal gender split in students studying chemistry at undergraduate level in the United Kingdom, but admitted that there is still much to be done, saying:

“The two recent RSC reports ‘Diversity Landscape of the Chemical Sciences’ and ‘Breaking the Barriers’ have highlighted some of the key issues. Although nearly 50% of undergraduate students studying to become chemists are female, the numbers reaching positions of seniority are considerably less.”

Professor Resmini was keen to stress that there are many supportive men in academia, and that’s something we mustn’t forget. Indeed, this was true even in Fulhame’s time. Thomas P. Smith, a member of the Philadelphia Chemical Society’s organizing committee, applauded her work, saying “Mrs. Fulham has now laid such bold claims to chemistry that we can no longer deny the sex the privilege of participating in this science also.” Which may sound patronising to 21st century ears, but it was 1810 after all. Women wouldn’t even be trusted to vote for another century, let alone do tricky science.

I think I’ve found Strumia’s limousine; it’s bright red, very loud, and can only manage short distances.

Speaking of patronising comments, another thing that Strumia said in his interview was, “It is not as if they send limousines to pick up boys wanting to study physics and build walls to keep out the women.”

This is one of those statements that manages, at the same time, to be both true and also utterly absurd. Pupils, undergraduates, post-grads and post-docs do not exist in some sort of magical vacuum until, one day, they are presented with a Grand Choice to continue, or not, with their scientific career. Their decision to stop, if it comes, is influenced by a thousand, often tiny, things. Constant, subtle, nudges which oh-so-gently push them towards, or away, and which start in the earliest years of childhood. You only need to spend five minutes watching the adverts on children’s television to see that girls and boys are expected to have very different interests.

Textbooks may be studied by girls, but they rarely mention the work of female scientists.

So let’s end with another of Professor Resmini’s comments: that the work of past female scientists deserves greater recognition than it has received. This could not be more true, and this lack of representation is exactly one of those nudges I mentioned. Pick up a chemistry textbook and look for the pictures of female scientists: there might be a photo of Marie Curie, if you’re lucky. Kathleen Lonsdale usually gets a mention in the section on benzene in post-GCSE texts. But all too often, that’s about it. On the other hand, pictures of Haber, J. J. Thompson, Rutherford, Avogadro and Mendeleev are common enough that most chemistry students could pick them out of a lineup.

We should ask ourselves about the message this quietly suggests: that women simply haven’t done any “serious” chemistry (this is not the case, of course) and… perhaps never will?

Online, things have begun to shift. Dr Jess Wade has famously spent many, many hours adding the scientific contributions of women to Wikipedia, for example. It’s time things changed in print, too. Perhaps we could begin by starting the rates of reaction chapter in chemistry texts with a mention of Fulhame’s groundbreaking work.


EDIT: After I posted this, I learned that the Breaking Chemical Bias project is currently taking suggestions on the missing women scientists in the chemistry curriculum. I filled in the form for Fulhame, naturally! If this post has made you think of any other good examples, do head on over and submit their names.


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