Tag Archives: chemistry

Rio Olympics – what are those gold medals worth?


Well, that’s a surprise.

Those gold medals athletes are working hard for at the Rio Olympics are not pure gold – just gold-plated silver. In fact, the of the Rio Olympics gold medals is 98.8% silver and only 1.2 % gold.

According to Compound Interest (The Composition of the Rio Olympics Medals):

“Giving out pure gold medals would be financially crippling for the International Olympic Committee, so unsurprisingly some compromises are involved.”

Olympic gold medals haven’t been 100% gold since the 1912 Olympics in Stockholm.

“Since then, they’ve actually been mainly made of silver, with a gold plating on top to give them the expected appearance.”

“Compositions are variable at different Olympics; for example, at the London 2012 Olympics the gold medals consisted of gold (1%), silver (92%) and copper (7%). The value of the Rio Olympics gold medal, based on its metal composition, is approximately $565. Contrast this with their value if they were composed of pure gold: their current market value would be $21,200!”

Seems like a lot of work is involved in moving from second to first place just for a thin plating of Gold.

Still, it’s the thought that counts.

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Chemistry is everywhere – even in those natural products


Here’s a thought – what of natural products came with a list of ingredients in the same way processed food does?

James Kennedy, an Australian chemistry teacher, has put together some images to illustrate what this would be like. And the article What if natural products came with a list of ingredients? reproduces the detailed infographics which show even the simplest of foods are anything but.

Kennedy said:

“I want to erode the fear that many people have of ‘chemicals’,’ and demonstrate that nature evolves compounds, mechanisms and structures far more complicated and unpredictable than anything we can produce in the lab.”


He added:

“With these graphics, I wanted to show that Chemistry is everywhere.”



Mind you – this won’t stop me reading the lists on packets of manufactured food. But it does show that one should not be automatically frightened by such lists. It is important to understand each component. A chemical is not dangerous, or unnatural, just because it is a chemical.

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What a pleasant surprise!


I don’t normally notice the special images on Google’s search page but was pleasantly surprised this morning to see this one.

It’s great to see some people are celebrating  Dmitri Mendeleev’s 182nd birthday. He was born February 8, 1834 , in the village of Verkhnie Aremzyani, near Tobolsk in Siberia.

Mendeleev is considered the “father” of the Periodic Table. I remember as a school student being fascinated by the periodic table and the early versions of it as the researchers of the time attempted to make sense of chemistry. That fascination remained with me as my study of chemistry became more advanced Today, the table is firmly based in quantum physics and can be derived directly from quantum considerations. Yet, in  those early days, no-one had that theoretical insight and derived the table from the chemical and physical properties of the then-known elements. The fact this enabled them to predict the existence of other elements, and the fact this lead to successful searches for them, has always inspired me.

So, Dmitri Mendeleev is one of the giants whose shoulders today’s scientists stand on. Only natural then that this commemorative ruble marking the 150th anniversary of his birth is a prized souvenir I picked in up Moscow 30 years ago.


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Fluoridation: Some simple chemistry

I often get comments about the chemistry of community water fluoridation which make clear the need for a simple explanation of some of the chemical concepts involved.  Here is an article I wrote some time ago on this but, for the life of me, I cannot remember where I put it on-line. So, I might be repeating myself – but, at least, it makes the article available. (t can also be downloaded as a pdf – just click on the title

Some chemistry issues involved in the fluoridation debate

Some claims made by critics of community water fluoridation (CWF) are chemically wrong. However, they may seem convincing to people without a chemical background.

Here I discuss some of the chemistry involved in the fluoridation debate and show how these claims are wrong.

What happens when a solid dissolves in water?

dissolving crystalIn a solid like ordinary salt (NaCl) the atoms exist as positively (Na+ cations) and negatively (Cl- anions) ions in a rigid lattice structure. This structure is generally stable as the ions are held together by electrostatic forces. But the structure can often be disrupted by water. The water molecular (H2O) is polar – it has a negatively charged end (the O atom) and a positively charged end (the H atoms).  These ends are attracted to the oppositely charged ions, surrounding them and bringing them into solution.

Once in solution, the ions are free from the rigid lattice and move about by themselves. The cations and anions are randomly mixed up through the volume of solution.

The ions are also hydrated. Depending on the chemical nature of the ion and its charge there may be different numbers of water molecules in the primary hydration shell right next to the ion. But other water molecules are also weakly associated outside the primary shell so we can think of anions and cations in solution as being sheathed by jackets of water molecules.


Can calcium fluoride exist in solution?

Some people suggest that natural forms of calcium fluoride are not toxic because the calcium modifies the fluoride. But technically there is no such thing as calcium fluoride in solution.

In nature fluoride is usually present as solid fluorite (calcium fluoride) or fluorapatite (a calcium phosphate containing fluoride and other ions). But when calcium fluoride dissolves the ions separate and the resulting solution is a random mixture of hydrated fluoride anions and hydrated calcium cations.

Fluorite (“natural” calcium fluoride) dissolves to form hydrated calcium cations and fluoride anions.

So our “natural” water containing “natural” fluoride actually does not contain calcium fluoride. Calcium fluoride does not exist as a separate species in solution. It contains a random mixture of hydrated fluoride anions and hydrated calcium cations.

We can describe this with the chemical formula:

CaF2  →  Ca2+(aq) + 2F(aq)

Where the (aq) notation identifies the ion as being hydrated in the solution.

What ions are in your drinking water?

In the real world, our “natural” water source contains more than this, though. It contains other ions which have dissolved from minerals or from other sources like rain and runoff.

In reality, our “natural” water should be considered as a solution of a range of randomly distributed anions and cations. Because of the nature of dissolved ions and the multiple ions present we cannot describe our “natural” water as containing “calcium fluoride,” “sodium chloride” or any other common chemical. These names are really only applicable to the ionic solids. Rather the water is a solution of hydrated Ca2+(aq), Na+(aq), F(aq), Cl(aq), etc. We have to characterise the water by the amounts of each ion present in solution.

The drinking water you get after treatment may contain less of some of the natural ions, or more if extra is added during (eg. F is naturally in the water source but sometimes supplementary fluoride is added to provide concentration optimum for dental health).




Your drinking water contains a random mixture of hydrated anions  and cations



You may think I have missed some obvious ions. For example –  H+(aq) and OH(aq). These are usually understood as present (at extremely low concentrations) and easily derived from the H2O molecule anyway.

H2O (aq)  ↔  H+(aq) + OH(aq)

In practice, water treatment plants adjust the pH (degree of acidity or alkalinity) of your water to very near neutral where the concentration of H+(aq) and OH(aq) are approximately the same and extremely low. They may do this by adding lime (containing Ca2+), ammonia (containing (NH4+) or other chemicals.

What about Al3+(aq)?- after all, chemicals like aluminium sulphate are added to remove colloidal material? However, this procedure works because in dilute solution Al3+(aq) hydrolyses (reacts with water) to form solid Al(OH)3 – so removing Al3+(aq) from solution.

Fluoridating chemicals

These are sometimes added during water treatment. Their purpose is to increase the fluoride (F) concentration to levels which are optimum of dental health. The chemicals used are generally fluorosilicic acid, sodium fluorosilicate or sodium fluoride.

Some critics of fluoridation argue these chemicals are toxic and calcium fluoride, a “natural” form of fluoride, is safe. They have even argued that community water fluoridation would be OK if CaF2 was used. But this argument is faulty for a number of reasons.

  • The lower toxicity of CaF2 is a result of its lower solubility. This is why some studies show the toxicity of high concentrations of fluoride can be reduced by addition of calcium salts.
  • Despite its low solubility CaF2 is sufficiently soluble to maintain a fluoride concentration of about 8 ppm (mg/L) – still far higher than the optimum concentrations aimed for in CWF (0.7 ppm).
  • The low solubility of CaF2 makes it impractical as a fluoridating chemical as if added as a solid uniform equilibrium concentrations would be difficult to achieve. If added as a liquid we would need a container almost as large as the water reservoir itself to store the near saturated CaF2
  • “Natural” CaF2 would be too impure for use in water treatment. Expensive processing (involving conversion to hydrofluoric acid and precipitation of CaF2) would be required to reduce the impurities.

Sometimes critics argue that “natural” fluoride in water is in the form of CaF2 which makes it safe because of the presence of Ca. But remember that CaF2 does not exist in solution which contains a random mixture of cations and anions. The hydrated Ca2+ ion is present in water naturally because it is derived from a range of sources besides fluoride minerals. It is also often added to water during treatment. So your drinking water already contains calcium, and usually at higher concentrations than if all the fluoride had been derived from “natural” CaF2

What about fluorosilicates?

Some critics of CWF claim that fluoride is not the problem. That because the most commonly used fluoridating chemicals are fluorosilicic acid (H2SiF6) and sodium fluorosilicate (Na2SiF6) the problem is the fluorosilicate species. They will even claim that we are drinking fluorosilicic acid and claim that there has been no testing of the safety of this chemical in drinking water.

But this claim is wrong. In fact, fluorosilicates react with water when diluted. They decompose to form silica and the hydrated fluoride anion. Consequently, safety studies made with sodium fluoride are completely relevant to these fluoridating chemicals when diluted.


A small amount of silica is normally present in drinking water. There is a tendency for this to polymerise and end up as solid SiO2.

Because of the extreme dilution of the fluorosilicate the liberated H+(aq) does not have a measurable effect on the pH mainly because of the equilibrium:

H2O (aq)  ↔  H+(aq) + OH(aq)

Anyway, the pH of the water is adjusted during treatment to neutral values (by the addition of acids, soda ash or lime) to prevent acid attack on pipes.

Chemicals in drinking water are extremely dilute

Critics will often wave pictures of bags of chemical being added to drinking water. Often they will illustrate their claimed danger of fluoridating chemicals by referring to safety data sheets. But these data sheets provide information on the storage, handling and disposal of the concentrated chemicals and have no relevance to the extremely dilute nature of the final drinking water.

The recommended optimum concentration of fluoride in drinking water is 0.7 ppm. Humans have difficulty imagining such extreme dilutions but the following figure provides some idea in day-to-day concepts.


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The chemical party

Just imagine teaching chemistry this way.

I guess you would have to lay off the juice, though. Otherwise, there could be some impossible bonding – and student recall would be low.

Thanks to: Sciencegasm shared Universitetet i Oslo (UiO)’s video.

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Why the internet annoys chemists

Here are some of chemist’s pet peeves chemists about discussion on social media and the internet in general. The list is from the article  5 simple chemistry facts that everyone should understand before talking about science posted on the blog The Logic of Science.

Everyone who has attempted to discuss issues like vaccination or fluoridation with opponents will have come across these arguments which the author describes as “based on a lack of knowledge about high school level chemistry.” This ignorance doesn’t seem to prevent the perpetrators of these arguments presenting with extreme confidence and fervour. When challenged they often question the scientific credibility of their critics and urge them to “do some research!”

1: Everything is made of chemicals

chemical free

The article points out:

“This seems like a simple concept, but many people seem to struggle greatly with it, so let’s get this straight: all matter is made of chemicals. You consist entirely of chemicals. All food (even organic food) consists entirely of chemicals. Herbal remedies consist entirely of chemicals, etc. So, when someone says something like, “I don’t vaccinate because I don’t want my child to be injected with chemicals,” they have just demonstrated how truly uninformed they are, and you can be absolutely certain that they don’t know what they are talking about because all matter is made of chemicals.”

Yet these arguments and terms like “chemical-free” seem to have gripped public consciousness. The only thing “chemical-free” is empty space!

A particular peeve of mine is the attitude advertisers seem to have that by declaring their product “chemical-free” they can get away with not identifying the real chemicals in their product. Recently at the supermarket I searched in vain for an indication of the chemicals in a package of sea salt. Genuinely intrigued to find what other salts were present, together with the majority sodium chloride, all I could find was the description that the product was “chemical-free!”

2: The dose makes the poison


“There is no such thing as a toxic chemical, there are only toxic doses. Let me say that again: all chemicals are safe at a low enough dose, and all chemicals are toxic at a high enough dose. This is a fundamental fact that people in the anti-science movement routinely ignore.”

Yet look at how the anti-science movement ignores this simple fact. Anti-fluoridationists who seem to think that have a foolproof argument by waving Material Safety Data Sheets for water treatment chemicals like fluorosilicic acid and sodium fluorosilicate. Such sheets supply information for people manufacturing, handling and transporting the concentrated chemical. They have absolutely no relevance for the person drinking the water coming out of their tap.

A little more sophisticated (although only a little) are the arguments based on scientific studies of rats administered chemicals at concentrations far higher than confronted by the ordinary consumer. Anti-fluoridationists spout so  much hot air citing studies of rats administered 100 ppm F or more in their drinking water to claim that drinking fluoridated water which has an F concentration of 0.7 ppm is harmful!

“The importance of this fact cannot be overstated. No chemical is inherently safe or inherently dangerous. So, the next time that someone tries to scare you about the “toxic chemicals” in your food, medicine, vaccines, detergents, etc. ask them for two pieces of information:

  1. What is the toxic dose in humans?
  2. What is the dose in the product in question?

Those two pieces of information are absolutely crucial to evaluating the safety of the product. You simply cannot know whether that chemical is dangerous without knowing the dose in the product and the dose at which it becomes toxic.”

3: There is no difference between “natural” and “synthetic” versions of a chemical

“I often hear people claim that “synthetic” chemicals (a.k.a. chemicals made in a lab) are not as good for you as their “natural” counterparts. The reality is that this represents a misunderstanding of literally the most fundamental concept of chemistry. The most basic unit of matter is the atom, and there are several different types of atoms known as elements. We combine these elements to make various molecules, and the combination of elements determines the molecule’s properties. The process by which those elements were combined is completely and totally irrelevant to how the final chemical behaves.

For example, water (a.k.a. dihydrogen monoxide) consists of three atoms: 2 hydrogens and 1 oxygen (hydrogen and oxygen are both elements). There are literally thousands of different chemical reactions that will produce water. In other words, we can make water thousands of different ways, but water always behaves in exactly the same way no matter how it was formed because it always consists of the same three atoms. Further, if given a vial of pure water, there isn’t a chemist anywhere in the world who could tell you how that water was produced because it would be completely identical to all of the other water everywhere on the planet. So, as long as the chemical structure is the same, it doesn’t matter if the chemical was extracted from a plant or synthesized in a lab.”

Yet, how often am I told that fluoridating chemicals are bad because they are “industrial,” “manufactured” or “synthetic.” The implication being that if we just dug these minerals out of the ground and dumped them in the water things would be quite OK. Of course, these people ignore the impurities present in “natural” ores and chemicals. Purification to a standard suitable for use in foods and drinking water requires chemical processing. Does treatment converting an “unsafe” ore or chemical to a safe (for consumption) chemical somehow make the chemical unsafe because it is now synthetic?

4: “Natural” chemicals are not automatically good and “artificial” chemicals are not automatically bad

“I often encounter people who will claim to agree with everything that I have said thus far, but they still insist that “artificial” chemicals (a.k.a. chemicals that simply are not found in nature) are bad for you and shouldn’t be consumed, injected, etc. There are several critical problems here. First, remember again that all chemicals are dangerous at a high enough doses and safe at a low enough dose. That is just as true for artificial chemicals as it is for natural chemicals. Second, this claim is nothing more than an appeal to nature fallacy. Nature is full of chemicals such as cyanide and arsenic that are dangerous at anything but a very low dose, so there is no reason to think that the “naturalness” of a chemical is an indicator of its healthiness.

Further, remember that chemicals are nothing more than arrangements of elements. There is absolutely no reason to think that nature has produced all of the best arrangements or that we are incapable of making an arrangement that is safe or even better than what nature produced. I constantly hear people say that we cannot improve on nature, but that is an utterly ludicrous and unsupportable claim, and I would challenge anyone to give me a logical syllogism that backs it up. Really think about this for a minute, if you are of the opinion that artificial chemicals should be avoided, try to defend that position. Ask yourself why you think that. Can you give me any reason to think that they are bad other than simply that they aren’t natural (which we have just established is a fallacy)?”

This nature = good, articifial=bad,  argument may appeal to the emotions of the chemo-phobic consumer, but it is just not rational.

5: A chemical’s properties are determined by the other chemicals that it is bound to

This is so obvious to anyone who has a rudimentary understanding of chemistry – but surprisingly it still gets challenged. How often have I come across anti-fluoride campaigners referring to fluorine containing chemicals like sarin gas (a chemical weapon), Prozac (a drug), hydrofluoric acid (a corrosive acid) – or even to fluorosilicates (used to treat water but decomposing on dilution) as if their properties were relevant to the fluoride in drinking water.

“Chemical compounds are made by combining different elements or even molecules, and the final product may not behave the same way as all of its individual parts. Sodium chloride is a classic example of this concept. Sodium is extremely reactive and will literally explode if it contacts water, and chlorine is very toxic at anything but an extremely low dose. Nevertheless, when we combine them we get sodium chloride, which is better known as table salt. Notice that table salt does not have the properties of either sodium or chlorine. It does not explode when it contacts water and you cannot get chlorine poisoning from it no matter how much of it you eat. The combination of those two elements changed their properties and it would be absurd to say that “salt is dangerous because it contains sodium.” The sodium in salt no longer behaves like sodium because it is bound to the chlorine. Therefore, when you hear a claim that something contains a dangerous chemical, make sure that the chemical isn’t bound to something that makes it safe.”

And therefore:

“So, claiming that “mercury is dangerous and vaccines contain mercury, therefore vaccines are dangerous” is no different from claiming that “sodium is dangerous and salt contains sodium, therefore salt is dangerous.””

Most dangerous and toxic  chemicals contain hydrogen, carbon, oxygen and/or nitrogen. That doesn’t make pure water toxic because it contains oxygen and hydrogen. Proteins, starches and sugars toxic because they contain hydrogen, oxygen carbon and nitrogen. Or the air we breath toxic because it contains oxygen and nitrogen.

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Fascinating and painless chemistry lessons

I had to select this video on the element rutherfordium because of the  New Zealand link of the scientist the element is named after.

It’s an interesting short lesson on rutherfordium and there is more where it came from – in fact one short video lesson for every element in the periodic table! Click on the image below to go to the interactive version of the periodic table.



You can find out more about the people who produced these videos from this University of Nottingham web site – Periodic Videos

This is a great, painless, way to learn some interesting chemistry.

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An answer to the anti-fluoride critics – in one image


Click image to enlarge. 

The chemical website Compound Interest, is producing a series of infograms to communicate some chemistry.  Here is an excellent one they produced on fluoride. I think it would make a great poster.

It is accompanied by some straightforward text describing the science behind fluoridation and countering a lot of the misinformation anti-fluoride propagandists promote.

Worth reading. See Fluoride & Water Fluoridation – An Undeserved Reputation?

The chemically minded may also be interested is some of their other infograms –  here are just a few examples:

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Anti-fluoride activists attempt to silence science

Roger Stratford, a local aspiring politician, wants scientist to shut up. He is campaigning against the fluoridation of Hamilton’s water supply (we have a referendum coming up) and is a member of Fluoride Free Hamilton. He is also campaigning for a seat on the Hamilton City Council.

But Roger seems to have a King Canute-like (or is it Walter Mitty-like) perception of his own powers. The Waikato Times this morning reports he wrote to the University of Waikato’s Chemistry Department requesting that it’s staff stop communicating their science (see Anti-fluoride campaigner tries to silence science). He objects to:

“the degree of casual support emanating from the chemistry department in local papers in support of the practice [of fluoridating water] . . . At Fluoride Free Hamilton we intend to limit the debate to the social science and public health aspects of fluoridation. . . . It would be appreciated if we could receive some confirmation from the chemistry department that it will remain publicly neutral on the matter. . . . Fluoride Free Hamilton does not have any issues with the chemistry department academically, it is the implications of modern science in which we differ.”

What a cheek – Fluoride Free Hamilton and Roger Stratford want a deal! They will talk only about social science and the chemists can STFU. Well, we all know that most of the issues around fluoridation are scientific, and mostly chemical. And the anti-fluoridation activists are spreading misinformation about that chemistry as fast and as widely as they possibly can.

What was Roger thinking?

My first whiff of Roger’s stupidity came with a comment of his on the Fluoride Free Hamilton Facebook page:

Facebook-before-2I contacted him asking if he had in fact written to the Chemistry Department. He Assured me in his reply:

“In my experience as a student the chemistry department doesn’t negotiate on anything, it was just a throwaway line of mine to get that Archer fellow from blogging. There is no reason to be alarmed.”

Well, I guess that’s a political answer – an implied but not a factual denial. Mind you, very quickly the comments on the Fluoride Free Hamilton Facebook page changed – see if you can guess what was deleted:


Well, I suppose that is politics. It is really a bit much to expect honesty and integrity from politicians, or from political activists like the Fluoride Free groups.

But I object very strongly to politicians, and political activists, who will do their earnest best to spread misinformation about science – and then tell scientists they have no right to comment on the issues.

See also:

Similar articles on fluoridation
Making sense of fluoride Facebook page
New Zealanders for fluoridation Facebook page

Singing about the periodic table

Most people here are probably familiar with Tom Lehrer‘s song – The Elements.

Well, for chemists here’s a new song about the elements – and the periodic table.

Actually, the video version – which depicts the elements in order on the periodic table may be useful as a memory tool for students.

The NEW Periodic Table Song (In Order).

Oh – there may also be a few more elements than in Lehrer’s time too.