What IS a chemical?

a_chemistry_teacher_explaining_an_experiment_8d41253v

You at the back there! Get your nose out of that dictionary and pay attention!

What do we mean when we use the word “chemical”? It seems like a simple enough question, but is it, really? I write about chemicals all the time – in fact my last WhatCulture article was about just that – and I’ve mentioned lots of different definitions before. But I’ll be honest, some of them have bothered me.

I don’t often like the definitions you find in dictionaries. Lexicography and chemistry don’t seem to be common bedfellows, and dictionary compilers haven’t, generally speaking, spent their formative years being incessantly nagged by weary chemistry teachers about their choice of vocabulary.

For example, in the Cambridge Dictionary we find:
any basic substance that is used in or produced by a reaction involving changes to atoms or molecules.”

Hm. Firstly, “basic” has a specific meaning in chemistry. Obviously the definition doesn’t mean to imply that acids aren’t chemicals, but it sort of accidentally does. Then there’s the implication that a chemical reaction has to be involved. So inert substances aren’t chemicals? Admittedly, “used in” doesn’t necessarily imply reacts – it could be some sort of inert solvent, say – but, again, it’s bothersome. Finally, “atoms or molecules”. Ionic substances not chemicals either, then?

Yes, it’s picky, but chemists are picky. Be glad that we are. A misplaced word, or even letter, on a label could have serious consequences. Trust me, you do not want to mix up the methanol with the ethanol if you’re planning cocktails. Similarly, fluorine is a whole other kettle of piranhas compared to fluoride ions. This stuff, excuse the pun, matters.

Dictionary definitions have their problems.

Dictionary definitions have their problems.

Let’s look at some more definitions (of the word as a noun):

The Free Dictionary tells us that a chemical is:
“A substance with a distinct molecular composition that is produced by or used in a chemical process.”

Merriam Webster says:
“of, relating to, used in, or produced by chemistry or the phenomena of chemistry <chemical reactions>”

And Dictionary.com goes with the simple:
“a substance produced by or used in a chemical process.”

That idea that a chemical reaction must be involved somehow seems to be pervasive. It’s understandable, since that’s the way the word is mostly used, but it’s not really right. Helium, after all, is still very much a chemical, despite being stubbornly unreactive.

Possibly the best of the bunch is found in the Oxford Living Dictionary:
“A distinct compound or substance, especially one which has been artificially prepared or purified.”

Not bad. Well done Oxford. No mention of chemical reactions here – it’s just a substance. We do most often think of chemicals as things which have been “prepared” somehow. Which is fair enough, although it can lead to trouble. In particular, ridiculous references to “chemical-free” which actually mean “this alternative stuff is naturally-occurring.” (Except of course it often isn’t: see this article about baby wipes.) The implication, of course, is that thing in question is safe(r), but there are lots and lots of very nasty chemicals in nature: natural does not mean safe.

You keep using that word. I do not think it means what you think it means.

Sometimes people will go the other way and say “everything is chemicals.” We know what this means, but it has its problems, too. Light isn’t a chemical. Sound isn’t a chemical. All right, those are forms of energy. What about neutrinos, then? Or a single proton? Or a single atom? Or, going the other way, some complicated bit of living (or once living) material? In one debate about this someone suggested to me that a “chemical was anything you could put in a jar,” at which point I pedantically said, “I keep coffee in a jar. Is that a chemical?” Obviously there are chemicals in coffee, it works from the “everything is chemicals” perspective, but it’s a single substance that’s not a chemical.

Language is annoying. This is why chemists like symbols and numbers so much.

Anyway, what have we learned? Firstly, something doesn’t necessarily have to be part of a chemical reaction to be a chemical. Secondly, we need to include the idea that it’s something with a defined composition (rather than a complex, variable mixture, like coffee), thirdly that chemical implies matter – light, sound etc don’t count, and fourthly that it also implies a certain quantity of stuff (we probably wouldn’t think of a single atom as a chemical, but collect a bunch together into a sample of gas and we probably would).

So with all that in mind, I think I shall go with:

So what IS a chemical?

A chemical is…

(Drum roll please….)

Any substance made of atoms, molecules and/or ions which has a fixed composition.

I’m not entirely convinced this is perfect, but I think it more or less works.

If you have a better idea, please do comment and let me know!


Like the Chronicle Flask’s Facebook page for regular updates, or follow @chronicleflask on Twitter. In need of a groovy new mug? Check out this page.


All comments are moderated. Abusive comments will be deleted, as will any comments referring to posts on this site which have had comments disabled.

 

Chemical paranoia: are they really going to get you?

chemicals1There are many warnings about nasty chemicals on the internet. “Ooh, chemicals are really BAD for you!!” type these paranoid types, on their computer made largely of polymers, with a screen containing liquid crystals, running on a lithium ion battery. “We’re being POISONED by all this stuff They’re putting into our food and water!!!” They cry, whilst drinking coffee that (naturally) contains caffeine, chlorogenic acids and umpteen other chemicals, having earlier swallowed some diphenhydramine for their many allergies and popping paracetamol pills for their terrible stress headache caused by all those capital letters and exclamation marks.

A quick glance at Snopes’ wonderful ‘Toxin du jour‘ page reveals a long list of stories which Snopes, the original home of internet urban legends, has cheerfully debunked, from the notion that aspartame is responsible for a cancer epidemic (it’s not), that microwaving plastic containers leaches dangerous chemicals into the food (it doesn’t) and the bizarre story of a mixture of certain type of baby formula and dog food causing a todler’s stomach to explode (do I need to state the obvious?)

Of course in writing this I fear I’m preaching to the converted, since people that forward on emails warning of the risk of deadly poisoning from re-using plastic drinking water bottles and the like never seem to be the sort of people to actually check their facts by, say, taking three seconds to type anything at all into a well-known search engine. And I therefore suspect they wouldn’t be reading this blog, it being dangerously factual and all. But for the sake of thoroughness, chemicals are all around us. The dictionary definition is “something with a distinct chemical composition that is produced by, or used in, a chemical process”. Most things are used in a chemical process somewhere, including such mundanities as water, oxygen and nitrogen. The only way anyone could avoid chemicals all together would be to lock themselves into a hermetically sealed chamber and pump all the air out. And that’s far from being a route to a long and healthy life.

“Ah, but,” the fearful cry, “we don’t mean NATURAL chemicals. We mean ARTIFICIAL ones. The ones chemists cook up in laboratories. Not nice natural things!”

Ah yes. Lovely, naturally-occurring chemicals. Like nicotine (the deadly nerve poison found in tobacco), lily of the valley (contains a high enough concentration of cardiac glycosides that even the water the flowers are placed in could be dangerously toxic), carbon monoxide (deadly by-product of the incomplete combustion of any carbon-based fuel, including all the ones you might be using in your house, such as wood, or coal, or gas) and botulinum toxin (the most acutely toxic substance known, naturally produced by the bacterium clostridium botulinum).

In fact, sometimes the synthetically produced is safer: for example salicylic acid (naturally-occurring in willow tree bark), while not particularly deadly is certainly a lot less friendly to the human digestive system than its chemically-modified cousin acetylsalicylic acid, otherwise known as aspirin.

And then there are food additives. They’re bad for you, right? They cause cancer, irritable bowl syndrome, hyperactivity, asthma, headaches, obesity, bad skin, bloating, unmanageable hair, purple rashes, gymphobia and notlikeingmondayitis, amongst other things. All of them*. You should definitely always buy foods that don’t have additives in. Everyone knows that.

Actually, no. In fact a lot of food additives keep us safe. Remember that botulinum toxin I mentioned up there? The most acutely toxic substance known? The bacterium that produces it grows in meat products. In fact, the German medical writer Justinus Kerner called it a “sausage poison” for that very reason. Why don’t people die from botulism more often? Because sodium nitrite (E250) is regularly added to meat products, and it does a great job of preventing clostridium botulinum from growing. It’s true that nitrites aren’t entirely controversy-free (in particular they’ve been linked to bowel cancer) but, and it’s a big but, the risk from botulism is much, much bigger than the small, theoretical, increase in your chances of developing cancer. Eating a botulism-laden sausage will kill you. Quickly. If you’re going to eat sausages at all, E250 is a good thing.

Many, many food additives are from entirely natural sources. Take the emulsifier lecithin (E322). It’s usually extracted from eggs or soy beans. Entirely homemade mayonnaise makes use of this chemical (whether knowingly or not) to keep the fat and water in the recipe from separating into layers. Ascorbic acid (E300) is used as an acidity-regulator and anti-oxidant, and its other name is good old vitamin C. Beeswax (E901) is routinely used as a glazing agent, espeically on apples, and there are a whole raft of colourings that are totally natural in origin, including caramel (E150a), Riboflavin (vitamin B2, E101) and beetroot red (E162). And by the way, those scary E numbers? The E just means they’re substances which have been approved for use within the European Union. In other words, they’ve been tested and shown to be safe. You could argue that those E’s are actually a very good thing. Who knew?

Then of course there’s E621, monosodium glutamate, used as a flavour enhancer (it produces the meaty flavour, umami). I feel sorry for poor old MSG, it gets a bad press. Blamed for everything from migraines to obesity to asthma (really this time). It’s been used for more than 100 years to season food, and is just the sodium salt of glutamic acid, one of the most abundant naturally-occurring amino acids. The MSG that’s added to food these days is mostly made by bacterial fermentation, not unlike yoghurt or vinegar. But glutamic acid turns up everywhere, or at least everywhere there’s protein, and therefore so do its salts. Lots of foods are naturally high in glutamate, including cheese, tomatoes, mushrooms and walnuts. It’s the same stuff, just with less sodium. So it’s safe to say that you can cheerfully ignore anyone who tells you that MSG is horribly bad for you, especially if they’re munching on a mushroom. Not to suggest that you should live off processed foods, of course, but you may do better to worry about the salt, sugar and fat content first.

In fact a lot of synthetic chemicals make our lives easier. Where would we be without medicines for example? (Not to be too blunt, probably dead.) Without the concoction that is toothpaste, most of us wouldn’t have our own teeth. Without chlorine in water we’d probably have died of typhoid or cholera (people arguing against it usually conveniently forget about those two, which used to kill by the tens of thousands). Just have a look around at all the plastic you use, and imagine for a second what life would be like without it: no soft contact lenses, no mobile phones, computers or TVs, no waterproof jacket or shoes, no biros, no packaging to keep food fresh and protected, no nylon or other synthetic fabrics… the list goes on.

So next time someone talks disparagingly about all those ‘chemicals’, ask them about all the ones they’re using right now. Or send them to Snopes. Or order that hermetically sealed, vacuum-pumped chamber. At least it’d be quiet.

——–

After I published this post, I came across this absolutely brilliant pic on Twitter: https://twitter.com/drandyrobertson/status/339991142793883648/photo/1
Fantastic!

*Given that I earlier claimed to be factual, I should admit that I may have made some of those up.