Magnesium – Mg – Atomic Number – 12! #GoSeahawks

NYE Space Needle, Seattle
Magnesium - Atomic Number 12
Magnesium – Atomic Number 12

What better element for Super Bowl week on my Periodic Table of Photography than Magnesium (Mg – Atomic Number 12). Go Seahawks!

Magnesium is at the other end of the density scale from the last element I featured – Tungsten – and is only 2/3 the density of Aluminium.  Alloys of Magnesium and Aluminium are used where weight (or lack of it) are important.  Cars, planes, luggage, laptop shells and also camera bodies.  So a key modern photography use – as well as a very old photography use – flash powder – as it ignites easily in air and burns with a very bright light.  Later, flash bulbs, or the flash cubes on Kodak Instamatics used Magnesium ribbon – ignited by an electrical charge. This property also led to its use in flares, sparklers and other fireworks.

This was New Years Eve a couple of years ago – but hopefully the fireworks will be loud this Sunday too!

NYE - Space Needle
NYE – Space Needle

Magnesium is also a very important element biologically, being the seventh most abundant element by mass in the body and integral to the working of many human enzymes.  In plants it is at the heart of chlorophyll – critical to photosynthesis and which leads to Oxygen production in green plants.

Magnesium is found in minerals such as magnesite and dolomite, but industrial production makes use of its abundance in sea water.  It was named after a district in Greece – Magnesia – where is was found along with similarly named Magnetite (an iron oxide) and Manganese (an element – Mn).

Magnesium Alloy wheels
Magnesium Alloy wheels

An experiment that I always remember from school was the thermite experiment – where Magnesium ribbon is used as a fuse to start the exothermic reaction of a mixture of an oxide and a metal – usually in chemistry lessons Iron Oxide and Aluminium – which then produces molten Iron and Aluminium Oxide. In our class this was done in a clay flower pot and the molten Iron stream out of the bottom…

Mag wheels became a common term for lightweight alloy wheels on cars – and these may or may not really be Magnesium or a Magnesium alloy – but the name stuck.

Epsom salts (hydrated Magnesium Sulphate) were originally discovered by a farmer in Epsom, England in 1618 – who noticed that his cows would not drink water from a particular well as it had a bitter taste.  The farmer noticed however that the water helped scratches and rashes to heal – and its fame spread. Another medicinal use of Magnesium salts is as an antacid (Magnesium Hydroxide) – such as Milk of Magnesia.

Following Magnesium I have another light weight metal – as I spell out AlIce – with Aluminium, Iodine and Cerium.

NYE Space Needle, Seattle
NYE Space Needle, Seattle

Tungsten – W – Who says heavy metal is boring?

Seattle - SR-99 near the Washington State Ferry Terminal

Tungsten (W – Atomic number 74) is one of the densest metals, 1.7 times heavier than lead, and up there with gold and uranium.  It has a very high melting point – 3413 °C – and is also alloyed with other metals to strengthen them.

Drill bit
Drill bit

These properties account for the major uses of tungsten, one which is dying out – the use as a filament in incandescent lamps (compact fluorescent and LED are much more efficient means of creating more light and less heat) and the other of creating very hard materials that withstand high temperatures.  Arc-welding and heating elements in furnaces, as well as drill tips are an example of these uses.  Tungsten Carbides (W2C and WC) are formed when powdered tungsten is heated with carbon – and these carbides are very hard – used for machining tools as well as armaments.

Torch light bulb
Torch light bulb

Tungsten is also known as Wolfram is some languages (where the W comes from…).  The ores it is produced from are wolframite and scheelite.  Tungsten comes from the Swedish tung sten meaning heavy stone.

Like Tin, Tungsten is known as a conflict mineral due to the unethical mining practices that have been observed in the Democratic Republic of the Congo.  Industrial users of Tungsten need to be able to trace the supply chain to source.

Talking of sources, the 4th richest deposits of Tungsten can be found in the UK, in Devon, and the increasing world price has seen the recent work to re-open the mines, at Hemerdon, Dartmoor.  This work will also see Tin mining return to Devon as this metal is also found in the same deposits.

Drill bit
Drill bit

Tungsten’s discovery is credited to Juan and Fausto Elhuyar who isolated the metal in 1783, although earlier work on identifying a new metal from the minerals goes to Peter Woulfe and Wilhelm Scheele.  Even earlier (more than 350 years ago) a Tungsten based pigment had been used in China for a unique peach colour in porcelain.

Other uses of Tungsten are for ballast due to its density – both for ocean and space going ships, as well as racing cars -and it is also used in Jewelery and making darts (why isn’t darts an Olympic sport yet?)

Tungsten is also the heaviest element known to have a biological function (next heaviest is Iodine – 53) – and is found in some bacteria in an enzyme that typically reduces carboxylic acids to aldehydes.  Tungsten is the only element ever to have been the subject of patent proceedings – and General Electric’s 1928 attempt was rejected – and the 1913  U.S. Patent1,082,933 overturned.

I struggled to find good photographic uses of Tungsten, (Industrial X-ray equipment maybe – or ballast to keep tripods steady) so finishing with a picture that shows Seattle’s Highway SR-99 – which is being replaced by a tunnel – being dug by ‘Bertha‘ whose teeth may use Tungsten.  The teeth on this largest ever tunnel boring machine are interchangeable depending on the rock/soil mix being tunneled – perhaps if ‘Bertha’ had her Tungsten Carbine teeth in that steel pipe would not have stopped her…

Seattle - SR-99 near the Washington State Ferry Terminal
Seattle – SR-99 near the Washington State Ferry Terminal

Oxygen – O – Lifegiver

Oxygen (O – Atomic number 8) is certainly something we couldn’t live without – or in fact couldn’t live at all if the concentrations in the atmosphere were much more or less.  But I guess if the levels had fluctuated more or been different then we wouldn’t have evolved quite the way we did. 

Rust - Ferrous Oxide
Rust – Ferrous Oxide

I found it much easier to concentrate on what Oxygen does to things as subjects for my photographs – is consumed when things burn – oxidises things, such as creating rust on iron, and is given off by the process of photosynthesis – from plants both in and under oceans – though not too deep as the process also requires light.

Plants and oceans - keeping the amount of oxygen in the atmosphere just right
Plants and oceans – keeping the amount of oxygen in the atmosphere just right

Industrially Oxygen is produced mostly by fractional distillation of liquefied air, with some being produced by passing over molecular sieves which absorb the nitrogen.  Main uses are the production of steel, and in the chemical industry for production of materials going into plastics and fabrics.  And of course life support.  Hospitals, divers, submariners and spacemen.  Oxygen is not used for blowing up the bags that fall at you in airplanes – but the oxygen is still flowing…

It always seems strange talking about discovering something that was there all the time (like America for example) but understanding the components of air and isolating the individual elements I think is a tangible discovery.  Two people are credited with Oxygen’s discovery – the Swede Carl Wilhelm Scheele (first) and England’s Joseph Priestley (first to publish) – although Antoine Lavoisier (and his wife) had a big part too in understanding what they had found.  

The isotopes of Oxygen – atomic weight 16, 17 and 18 – and their relative abundance and the fact that water containing these isotopes evaporates at different rates – which is also temperature dependant has helped with both dating and identifying temperature fluctuations in the past – by analysis of ice cores.

Natural gas - needs oxygen to burn
Natural gas – needs oxygen to burn

Tin – Sn – Putting the reversal into reversal film

Tin (Sn – Atomic number 50) is a metal, except when it isn’t.  White Tin, or β Tin is a metal, but there is also another allotrope – α Tin – grey Tin which has no metallic properties at all.  This semi-conductor is stable under 13.2 °C, and can form from white Tin in a process known as Tin pest.  The most common uses of (white) Tin are as a component of solder and for coating steel to prevent corrosion – one example of which is to make ‘tins’ – or cans if you prefer. Solder was made from Tin and Lead – but other alloys with Tin are now used to avoid the toxic Lead.  Tin pest is more of a problem in Lead -free solder and can lead to joint integrity issues.  If you are not familiar with allotropes – carbon as diamond or graphite is a more common example.

Solder - which contains Tin
Solder joints on a circuit board on a hard drive

The previous posting was about Yttrium – which had just one stable isotope – and in contrast Tin has 10 – due to it having a magic number of protons.  Tin has been used since around 3000 BC and its addition to copper to form alloys like bronze heralded in a new age.  Tin mines in Devon and Cornwall operated from around 2150 BC – with the last one closing as recently as 1998.  This made the region one of the earliest parts of Britain to trade with the rest of Europe and even the Middle East –  both before and after the Roman invasion.

Tin lid
Tin lid

The main mineral that has always been the primary source of Tin is cassiterite, and this is now classified as a conflict mineral due to the conflict waged over control of the land where large deposits are fund – such as in the eastern parts of the Democratic Republic of the Congo.  Companies in the United States that use materials that come from conflict minerals need to be able to audit their supply chains to prove the origins – following the 2010 Dodd-Frank Wall Street Reform and Consumer Protection Act.

Now for the photography connection – and Tin(II) Chloride – SnCl2 – otherwise known as stannous chloride – is used in the ‘E-6’ photographic process for producing colour transparancies, or slides.  When I worked in a photo research lab the E-6 reversal bath was one of the formulations I worked on.  Stannous chloride is a reducing agent, and in the reversal bath it performs the same role that light does in exposing the silver halides that remains after the ‘First Developer’ has produced basically a black and white negative.  In print photography you take a negative – shine light through onto paper and then develop – for slides this all happens in the same piece of film.

Tin lid
Tin lid

The reversal bath prepares the reversed image by ‘exposing’ all the silver halide that has not been developed to a silver image in the first developer (which is a black and white developer)   and this silver halide can then be developed in the colour developer to product the positive image. The colour actually comes from dyes in the film reacting with the local oxidized developer in three layers sensitive to different parts of the spectrum.   A good article that show this effect weel is the Kodak one – Processing Solutions and their Effects.  The E-6 process applies to Kodak’s Ektachrome and Fuji’s Fujichrome and others – but probably the most famous transparency film – Kodachrome – goes through a slightly different process.  It has no dyes in the film (so the film can actually be thinner) but instead after first development it goes through a series of exposures to different coloured light and development in three different colour developers that contain the dyes – so building up the colour image without chemical reversal.  E-6 is a process you can do at home without too much difficulty – Kodachrome K-14 was much more involved – and I say ‘was’ as production of Kodachrome film ceased in 2009 and the last roles were processed in December 2010.

Next up in my photographic journey through the Periodic Table is Oxygen – and I might need to get a bit creative with a photo depicting O2.

Circuit board with solder joints
Circuit board with solder joints

Yttrium – Y – Clear white light

Yttrium (Y – Atomic number 39) is another transition metals (like Iron) and was named after the town in Sweden, Ytterby, where the mineral (Ytterbite) in which it was first found was picked up from a quarry. Today Yttrium has a number of uses – as its oxide it is added to glass for camera lenses to improve heat and shock resistance.  We have all starred at it as it was used for making phosphors, such as the red ones in used in televisions (non flat screen), and it is a regular additive to magnesium and aluminium alloys to improve strength  – and probably its most important current use is in the production of white LEDs. So a couple of photography related uses.

White LED from my Christmas lights
White LED from my Christmas lights

I must get a better lens for macros… Yttrium is fairly common – the 28th most abundant element in the earths crust, found in soil and sea water – and strangely found in cabbage (not enough to worry about though).  It is very similar to the lanthanides, its close neighbours in the periodic table, and mostly obtained from the same rare earth minerals.

Camera lens with periodic table reflection
Camera lens with periodic table reflection

The way it is used in white LEDs is interesting, as Cesium doped Yttrium Aluminium Garnet (YAG, Y3Al5O12) – it is a phosphor that emits a yellow light.  As a coating in high brightness blue InGaN diodes this converts some of the blue light to yellow – giving an overall white light.  The spectrum coverage is not perfect though – so even though it appears white the colour rendering isn’t ideal.  It is a fascinating (to me anyway) topic colour rendering – and has always been a challenge for colour photography to get an accurate representation of scenes that match to the way our eyes interpret them.  The colour can be affected very much by the light source – and it the white light doesn’t cover the full visibile spectrum then some colours just won’t look as expected – and this can be further challenged by the viewing conditions.  More over at Wikipedia – and the book The Reproduction of Colour gives lots more detail for those interested.

On final fun fact – and I’m sure gas mantles are something that few will remember – but these were used for propane lanterns (I remember them from caravan holidays) and where often used in the science lab as a demonstration of Geiger counters – as they used to be made with thorium which is radioactive.  Yttrium has replaced thorium now, so I guess science teachers bought up the old stock to keep the demonstrations going!

That finishes my first word – Fe Br U Ar Y – so next up come Tin, Oxygen and Tungsten – one life giver between two metals often connected with war and conflict – and the word is Sn O W.

Camera Lens

Argon – Ar – A good for nothing gas

Argon (Ar – Atomic number 18) is the third most abundant gas in the atmosphere, after nitrogen and oxygen, and on the increase – albeit slowly.  Not really good for nothing – but good for doing nothing – one of the inert gases.  Most of its uses rely on this fact – whether it is keeping wine fresh or allowing metals to be welded in an inert atmosphere – or protecting the filament of a light bulb.

Light bulb - with reflection of the periodic table
Argon filled incandescent light bulb

I was going to say that Argon replace the vacuum that had been used to allow filaments in early light bulb to glow without burning away – but not sure it makes sense that a vacuum can be replaced.  The word Argon comes from the Greek word  αργον – meaning lazy – as it can’t be bothered to react.  There are very few compounds of Argon – argon fluorohydride is one – but needs very low temperatures to survive (40 kelvin).  (Just in case you are wondering – like I was – the root for the Argonauts was Argo – from the word meaning swift)

Argon in the Periodic table seen through a bulb
Argon through Argon

In the intro I mentioned the volume of Argon in the atmosphere is increasing (around 0.94% currently) and this is due to the decay of 40K to 40Ar by electron capture.  This fact is also used for dating rocks – as the amount of Ar is indicative of the age or the rock.

Light Bulb

Another good periodic table fact is that in early periodic tables by Mendelev, Potassium preceded Argon – as the order was first based on atomic mass – and even though Argon has one fewer protons than Potassium, the most abundant isotopes of Argon have more neutrons – and hence the relative atomic mass is higher for Argon.  The nature of Argon compared to Potassium seemed to fit the other order better – and the periodic table was soon changed to follow atomic number.

The excellent interactive Periodic Table from the Royal Society of Chemistry is the one seen in the background of these photographs.

U – Uranium – Not that sort of photo bomb

Uranium (U – Atomic number 92) has photography in its history when Henri Becquerel had left a sample of Uranium, in his Paris lab in 1896, on top of a photographic plate.  On development the plate appeared to have been exposed to something – and Henri deduced that some invisible rays were being given off – and radioactivity was discovered.  The element had been first isolated, also in Paris, by Eugène Peligot 55 years earlier.  In thinking of a photo for my Uranium post I thought back to several visits, when I was much younger, to several nuclear power stations in the UK.  I had been fascinated by radiation and was fortunate to have visits to several plants both by arrangement from college – but also on family holidays.  No photos though.  I did however remember a photo with a Uranium connection – one I took at the Farnborough Air Sciences Trust (FAST) – of a schematic of WE177 nuclear weapon attached to a replica of the last deployed air-launched nuclear bomb by the UK.  I also remembered the photography conditions at FAST – were they were happy for people to take photos for personal use.  And to be honest, my photo taken on a wet day wasn’t the best…  However the schematic bore a copyright notice from Brian Burnell, and I was fortunate enough not only to find more information on Brian (the power of Bing!) – but to get permission to use his schematic in place of my poor photo.  Thanks to Brian!

Sectional of a WE177
Sectional of a WE177

Brian has also captured background on this fascinating and chilling time in world history on his web site .  Growing up through the 60’s and 70’s it is interesting reading Brian’s articles.  Always know where your protractor is!

I’m a big fan of the potential for nuclear energy – and some countries have embraced and really succeeded with the technology – France for example – but there is the potential for disaster too.  And we can never really know where we might be if nuclear weapons hadn’t been invented – but the genie is out of the bottle.

On a lighter note, much lighter (and the pun is there for those who want it) – next up is Argon – Atomic number 18.