The Duplo kit for building atoms would contain only three types of building blocks.

Protons

The number of proton defines the identity of the atom (which element in the periodic table).

Each proton has a charge of +1 and an atomic mass of 1. Protons are found in the centre of an atom in the nucleus and absolutely hate being held so close to each other. Imagine having several magnets and trying to push all the north poles together in a very very small space – this is how reluctant protons are to be near each other only more so. Neutrons are included in the nucleus to mediate the situation. The more protons you have the more neutrons are needed to stop the protons splitting off from the main group (radioactive decay).

Neutrons

The UN peacekeepers of the subatomic world.

Each neutron has a mass almost the same as the proton. As their name suggests neutrons are completely neutral so the number included in the nucleus of the atom will have no influence on the identity of the atom and little impact on its personality. This is how hydrogen can have none, one or two neutrons in its nucleus and still be hydrogen and behave almost exactly the same even if it has put on a bit of weight.

Electrons

Give atoms their personality.

Electrons are light and fast moving but trapped on a fixed path orbiting around the nucleus (think hamster in a wheel). Electrons have a charge of -1 so the number of electrons equals the number of protons to give an atom with no overall charge. If the atom (beryllium) has four protons (+4) it will have four electrons (-4) in what is technically called the zero oxidation state – Be(0).

More than one hamster on a wheel is ridiculous so things need to be organised. Electrons are arranged into shells and subshells in a 2, 2 + 6, 2 + 6, 2 + 10 + 6, 2 + 10 + 6,…. pattern. If you read the periodic table from left to right as you would words in a book, starting from hydrogen you will see that the number of elements in each block matches the pattern of electrons in shells. This is not a coincidence.

For example, …

Hydrogen – 1 electron – 2 wheels, 1 hamster

Helium – 2 electrons – 2 wheels, 2 hamsters running in opposite directions. Symmetrical and even – this is a complete shell.

Lithium – 3 electrons – 2 wheels, 2 hamsters running in opposite directions; 2 bigger wheels, 1 hamster. A wheel without a hamster is a sad sight so lithium will readily give away its outermost hamster (electron) to obtain a complete shell of hamsters and wheels.

Beryllium – 4 electrons – 2 wheels, 2 hamsters running in opposite directions; 2 bigger wheels, 2 hamsters running in opposite directions.

And so on and so on…… This arrangement of wheels and hamsters is called the ‘Pauli Exclusion Principle’ – use it in conversation, impress your friends.

All atoms are aiming for an ideal number of electrons 2, 10, 18, 36, 54 etc. as this number gives full outer shells like the enviable Noble gases. To achieve this atoms towards the left side of the periodic table will give electrons away to reach one of the magic numbers (for example, sodium with 11 electrons will give away one to reach the happy number 10). Elements to the right of the periodic table will take electrons (fluorine will steal one electron to make up a total of 10) and elements in the middle will share with other atoms to give the outward appearance of completeness.

The by-product of all this electron swapping and sharing is chemical bonds and molecules or compounds and an entire scientific discipline.

@RotwangsRobot

Images by @SciCommStudios

Boron’s quiet brilliance and versatility all stems from its being three electrons away form the ‘ideal’ helium structure. Giving away three electrons is a big ask, especially when that only leaves you with two, so boron likes to share. Boron will share each of its three outer electrons in exchange for a share of an electron from three other atoms (totalling six). Admittedly some elements are very selfish and tend to the hog the electrons offered by boron but others are more generous. Boron will even shuffle everything round to accommodate two electrons from one donor atom to make up a full, happy, complete shell or octet. See supplementary post on atomic structure for a better explanation (due later this week).

Boron’s uses include: Pyrex (or borosilicate) cookware in your kitchen as it is more resistant to thermal shock than conventional glass; neodymium magnets (and you thought they just contained neodymium); insecticides (in the form of boric acid); bullet proof vests (in the form of boron carbide) and to keep swimming pools clean (again in the form of boric acid).

There is a good chance that boron is also sitting in your washing powder, in the form of sodium perborate, ready to do its bit oxidising, and thereby bleaching, stains on your washing. You may also have seen boxes of borax in pharmacies allegedly for use in laundry but I suspect most of these are now sold to teachers and parents wanting to do ‘goo‘ demonstrations with their kids.

Boron also forms compounds with hydrogen called Boranes which, similarly to their carbon equivalents, burn to release a huge amount of energy. The story I was told as an undergraduate went something like this. During the height of the cold war an American spy managed to sneak in to a rocket testing facility in Russia. Whilst there he observed a test launch and to his surprise saw green flames billowing out of the rocket’s thrusters. He quickly sent a message back to America describing his observations and American scientists deduced that the Russians were experimenting with borane fuels. These highly reactive compounds were known to be very effective rocket fuels but were difficult to handle and toxic. The Americans had carried out relatively little research up to then, and loathed to be left behind by the Russians, they began pouring money into researching borane technology.

It later emerged that the spy was colour blind and that the flames he had observed were orange all along. The use of boranes as fuel for rockets and aircraft, like the Lockheed SR-71 ‘Blackbird’, seems to have ended. However, boron still occasionally makes a star turn in pyrotechnics such as flares and fireworks – just look for the characteristic green flames.

Brace yourself for greatness. Next week its carbon.

@RotwangsRobot

Images by @SciCommStudios

On Earth, and in the rest of the universe, beryllium (Be) is rare. With four electrons beryllium is only two electrons away from a happy stable arrangement like helium. It is fairly easy for beryllium to lose these two electrons to form Be2+ and form bonds with other atoms to make compounds. This means all the beryllium found naturally on earth is tied up in compounds with other elements. The most common place to find beryllium, for those rich enough, is in emeralds. It is also found in a range of other gemstones with the names varying with the colour. The colours have nothing to do with beryllium but come from trace impurities such as chromium or manganese in the crystals.

The element beryllium is a metal with some unusual properties. Beryllium is light, strong and has a high melting point which makes it an ideal choice for the space industry. Rocket nozzles made with beryllium alloys don’t deform under the high temperature conditions they experience.

A more unusual use of the metal is as windows for X-ray detectors and as the beam pipe for the Large Hadron Collider. The LHC has a huge doughnut shaped pipe through which scientists accelerate protons towards each other (I like to think of the protons as two piñatas smashed together to find out what’s inside). Because beryllium metal is strong and inflexible high vacuums can be created inside the pipe, the particle debris from the proton collisions are very small, as is the nucleus of beryllium, meaning the particles travel through the beryllium pipe to the detectors relatively undisturbed.

Space vehicles, big budget physics and jewellery – so far so glitzy. What about the dark side?

Beryllium and its compounds are toxic. Be2+ is very similar in size and character to magnesium, in the form of Mg2+, which carries out a huge number of vital functions in the human body. Be2+ will be absorbed by the body mistaking it for Mg2+ but it won’t work as well leading to a breakdown in vital processes at a cellular level. Beryllium’s rarity means we will not be exposed to dangerous levels in our everyday life but metal workers in the space industry were once at greater risk of exposure – beryllium is particularly dangerous when its dust is inhaled. Huge improvements in working practices in the space industry have now reduced the risks to a minimum.

The cruel twist to poisoning cases is that many compounds of beryllium taste like sugar. When the element was first discovered it was suggested its name should be glucinum or glucinium after the Greek word for sweet.

There are no recorded cases of deliberate beryllium poisoning but this isn’t surprising. Although the sweet taste would mean beryllium would be easy to disguise in food it would be a poor choice for wannabe poisoners. Beryllium’s rarity is an insurance against murder but its high melting point means it is also very difficult to work with. The first ever ingot of beryllium was cast in 1898, 70 years after the initial discovery of the element.

Next week, its not boring, its boron.

@RotwangsRobot

Images by @SciCommStudios

To me lithium is like a naïve kid, eager to please and in awe of helium (the cool and aloof distant cousin). Lithium tries to mimic helium by giving away one of its three electrons to any other atom that will take it. As is often the case with two people wearing identical clothes, one will look effortlessly sophisticated, while the other will look faintly ridiculous. Lithium looks ridiculous. Just because lithium is wearing the same number of electrons as helium does not mean they look the same.

Giving away and sharing electrons are how atoms make friends. Losing an electron leaves the atom with a positive charge, in this case Li+, which is attracted to any atom or molecule with a negative charge. Giving away an electron also makes Li+ very small and it is often dwarfed by the atom that has taken its electron making a very uneven pairing. Li+ still sticks loyally to its domineering partner. This generosity means you will never dig up a lump of lithium the way you could a nugget of gold. If most of the lithium on the planet is in the form Li+ we should talk about some of the things Li+ can do.

Lithium’s willingness (or desperate need for appreciation) to give away its electron means it is a great candidate for use in batteries. Electrical energy is simply something that has a charge which is moving. This can be the electron from lithium moving towards another element that will accept it. This is how disposable or coin batteries work. In the rechargeable batteries we have in laptops and mobile phones it is the Li+ that shuttles between the positive and negative ends of the battery (depending on whether it is being charged or being used).

The most unexpected use of lithium is in the treatment of mental illness. Lithium has been found to be most effective in the treatment of Bipolar disorder. Li+ is the active ingredient in the drug lithium carbonate but no one knows exactly how it works. The important bit is that it works and lithium carbonate is the standard by which all new drugs for treating Bipolar disorder are judged. The pharmaceutical use of lithium is all the more surprising because it has no known biological role in the human body. Studies with rats seem to show a need for a very small amount of lithium in their diet (equivalent to about 1mg per day for humans) but the reasons for this are unclear.

Next week’s blog post is to die for! Its Beryllium.

@RotwangsRobot

Images by @SciCommStudios

In 1868 Pierre Janssen and Norman Lockyer noticed something unusual about the light coming from our sun during an eclipse. The rainbow of light that comes from our sun is not perfect – there are gaps in the colours (see image). The black lines occur because atoms in the sun absorbs wavelengths of light specific to the type of element – like a fingerprint. This bar code of the sun tells us what it is made of. Some black lines observed in the 1868 solar eclipse did not match the fingerprint of any known element – Jansen and Lockyer had discovered something new and they called it Helium from Helios meaning ‘sun’.

Helium wasn’t isolated on Earth until 1895 by Sir William Ramsey – several others isolated the same gas that year but Ramsey got in there first. It was thought to be very rare element on Earth because Helium is so light it can escape Earth’s gravitational pull and float out in to space. Then in 1903 miners in Kansas came across a huge underground cache. They tried to light the jet of gas as it escaped from a crack in the ground, but it wouldn’t catch because helium doesn’t react with oxygen, or anything else for that matter.

The Periodic Table was first conceived as a whole in 1869 by Mendeleev (youngest of 14, formulated state standards for the production of vodka and didn’t believe in atoms). Many people before Mendeleev had attempted to arrange the elements in some kind of order with varying degrees of success. Mendeleev’s genius was to arrange the elements systematically by weight to highlight similarities between some of the elements. A regular pattern emerged and this was so compelling that Mendeleev was able to leave gaps in his table where he expected new elements to be discovered. To the astonishment of his fellow scientists he also predicted the physical properties of these elements based on their position in his newly formulated table and he was proved correct.

Since Mendeleev there have been many versions of the periodic table, three dimensional versions, spiral versions and then the table we are all now familiar with – a castle with unequal turrets at each end. The 118 bricks of the castle are the elements, each unique and with its own story to tell.

(Short Periodic Tale introductory animation)

The discovery of hydrogen can be attributed to three people – or one of three people depending who you like most – Boyle (the father of modern chemistry, author of ‘The Sceptical Chymist’ and bad speller); Cavendish (genius, gynophobic – Google it, and cousin of the Duchess of Devonshire – you know, Keira Knightly in that film); and finally, Lavoisier (scientist, established the metric system and guillotined in the revolution).

Boyle, in 1671, isolated a gas that was evolved when acid was poured on iron filings. Cavendish, in 1781, established that the gas was an element and not a compound or mixture but he thought it was phlogiston (expect supplementary blog on phlogiston). Lavoisier, in 1783, gave the gas the name hydrogen, meaning water creator.

Hydrogen was the first element to be created after the Big Bang and today 90% of all atoms in the universe are hydrogen. Hydrogen comes in three forms – 1H – Hydrogen, with one proton and one electron; 2D – Deuterium, with one proton, one electron and one neutron; 3T – Tritium, with one proton, one electron and two neutrons. Tritium is not so interesting so I am going to ignore it – considering it occurs in only trace amounts in the upper atmosphere this is not difficult to achieve.

Deuterium is chemically very similar to hydrogen but the neutron makes deuterium almost twice as heavy. The effect this has on its chemistry is subtle and affects bond length and bond energy. The differences compared to ordinary hydrogen are enough that deuterated water (D2O) or heavy water is slightly toxic to eukaryotic organisms – a 50% substitution of heavy water can cause death. Several goldfish and one mouse have made the ultimate sacrifice, although there are no recorded deaths, accidental or otherwise, of humans. Deuterium makes up only 1% of all hydrogen in the universe, considering you could drink around 5 litres of heavy water with no appreciable side effects (other then frequent trips to the toilet) it is unlikely you will encounter enough in your day to day life to cause you any problems.

This reminds me of a tale that went round while I was a student. The story went that the CIA had made a deuterated dog where all the dog’s hydrogen atoms were deuterium. How and, more importantly, why was never discussed. The dog was fed deuterated food and water to maintain its deuterated status. This is obviously bollocks, and not even the dog’s bollocks. Maybe a particularly geeky student overheard a conversation about a ‘heavy dog’ and got the wrong end of the stick. Maybe I spent too much time around the ether bottle.

Bizarrely the CIA’s dog, if it could be made, would be invisible to a MRI scanner. The dog would still be clearly visible to the naked eye so apart from confusing the staff operating the scanner I can see no advantage to this. Its the hydrogen atoms in our body that show up in MRI scans because the proton at the Centre of the atom behaves like a tiny magnet. Inside the scanner each tiny hydrogen magnet in our body aligns itself with the MRI’s huge magnetic field (just as two ordinary magnets will align themselves north-south if you bring them close together). A short pulse of radio waves is enough energy to knock the protons out of alignment. The MRI detects to energy emitted by the protons as they return to their aligned state and can use this to create an image. Deuterium, with a proton and neutron at the Centre of the atom, does not behave like a magnet and is therefore invisible to the MRI scanner.

If the periodic table is a family then hydrogen is the black sheep. The small runty one that turns up at every gathering but no one knows who they are really related to. There is a resemblance to the alkali metals (group 1), but then also the halogens (group 17), and in fact hydrogen doesn’t really look like any group. Maybe hydrogen’s mum was friendly with the postman. This is why hydrogen is often seen floating aimlessly above the rest of the periodic table. Without it’s solitary electron (which it is quite happy to give away) it becomes a proton which isn’t even an atom or an ion but a subatomic particle.

When hydrogen bonds to an alkali metal it behaves like a halide and when its bonded to a halide it behaves like an alkali metal. Hydrogen normally makes only one bond per atom but hydrogen isn’t normal so it also forms bridging bonds between two or more atoms called, unsurprisingly, hydrogen-bonds. These bridging bonds may be unusual but they are essential to life, allowing water (H2O) to be liquid at temperatures commonly experienced on this planet and holding DNA strands together.

Hydrogen is so ubiquitous that listing all its roles in the chemistry of our everyday life I would be here forever and I promised more blogs on other elements. One of the more well known and interesting roles has been in transport. Hydrogen, going around as it normally does as a pair of hydrogen atoms, is lighter than air, a property exploited for use in air ships. The highly flammable nature of hydrogen (or the huge amount of energy released when it forms a bond with oxygen if you look at it slightly differently) stopped its use in air ships after the now infamous Hindenburg disaster. In defense of those that built the Hindenburg many believe it was the skin of the air ship that burnt initially rather than the hydrogen.

Hydrogen has continued to be used as a fuel but in liquid form and for rockets. Liquid hydrogen and liquid oxygen are mixed and ignited to generate the huge amount of energy needed to launch craft away from Earth’s gravitational pull and out in to space . Due to hydrogen’s very small size and very light weight making hydrogen liquid and storing it is no trivial matter. Hydrogen becomes liquid at temperatures below -253 Celsius and has to be stored in very sturdy containers else the tiny molecules will leak out.

We now look to hydrogen to be the fuel of the future through fuel cells – combining hydrogen and oxygen to form water but using a catalyst to convert the energy released into useable electricity. Again, storage of hydrogen is one of the major problems that needs to be overcome. Many researchers have explored the properties of platinum and palladium which have the ability to store huge amounts of hydrogen – but that is a story for another blog post.

There is much more to hydrogen for example, a metallic liquid form of the element may form the core of distant planets, but there is simply not enough time or space here to explore them all. I hope this has fed your imagination and encouraged you to find out more.

See you next week for Helium.

@RotwangsRobot

Images by @SciCommStudios

And so it begins...

So this is a New Year’s resolution type thing..after eating more veg, getting more exercise and taking over the world. Blogging seems easier than all the other resolutions but I could be proved wrong any minute.

The plan for this blog is to write interesting things about chemistry – yes it is possible! Plus any other sciencey thing that strikes us as fun, quirky or just makes us go ‘Y’wha?’.

Starting from the start I (@rotwangsrobot) plan to write a blog a week about the periodic table from Hydrogen all the way down until I get a life. Sometime around 7th or 8th January please look out for post number 2 – Hydrogen. If there is anyone reading still reading you can hold me to this.

Now I have to go away and plan this (including excuses for when I fail).

@RotwangsRobot