parseerror.com / ~pizza / periodic-table-table.html

Updated 2008-02-12

A Periodic Table Table

On the Use of Color
I have lots of information to convey and I try to do so using tables and color codes to express various pieces of information. There is no overall, inherent meaning to any color, they are used per-graph.
One day I stumbled across Theodore Gray's Wooden Periodic Table Table — the man (a capable amateur carpenter and avid math and science geek) created a wooden conference table in the shape of the periodic table of elements. Each tile is in fact a box, removing the top tile reveals a sample of the element itself! I was absolutely enthralled, both with the concept of a physical periodic table table and with the website set up around the table and Mr. Gray's ever-growing element collection. I've spent months perusing the site and I never tire of it. This is a rare project, one that requires time, dedication and skill to produce, results in a practical, functional object (a conference table) and yet is educational and makes learning the elements easy and fun.

But one thing bothered me: why use wood for the tiles? Why cover the beautiful elements you've worked so hard to collect and melt and cast and shape behind a piece of wood which has nothing to do with the element it represents?

Why not construct the tile out of the element itself?

This simple idea combines both the scientific knowledge and classification of an element with its actual physical representation. How much more striking is a heavy, shiny, gold-plated Au tile? A Carbon tile cut from smooth, dark graphite? A Hg tile containing silvery liquid Mercury? A fragile yellow Sulfur tile? (I've broken two already) A Tungsten tile that weighs 11 times as much as a Magnesium tile? Furthermore I believe that forcing the elements into the same basic form magnifies differences in their color, texture, reflectivity and weight.

That was it; I had to do it. I'm neither a chemist nor a metallurgist nor a carpenter; but I believe that this is a project worth doing. What better way to learn about the world than to study and work with the elements from which all things derive?

No longer will the elements simply be names and numbers; one must familiarize one's self with the real-world properties of each element. Is it toxic? Is it radioactive? Can I make a tile out of it? Would the tile fall apart? Can I engrave a tile made from this element? How much does it cost? Where can I get it? Can I cut it? Can I melt it? Can I prevent it from melting? Does it react with glass? Can I cast it? Are the shavings going to spontaneously oxidize and catch fire? Are large chunks of it going to explode if it touches water? Is it harder than my saw? Does it have a higher melting point than the materials from which I'm building my furnace?

So let's get to it...

Progress Report

I'm sticking this section near the top, out of logical order, so anyone checking back doesn't have to scroll to the bottom.

2008-02-12
Here is a progress report on element obtainment (elements I need are in red):

      
Li Be B C        
Na Mg Al Si P S    
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge   Se Br  
Rb Sr Y Zr Nb Mo   Ru Rh Pd Ag Cd In Sn Sb Te I  
  Ba Hf Ta W Re Os Ir Pt Au Hg   Pb Bi      
                                 
La Ce Pr Nd   Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
                             

Everything not in red I have in some reasonable quantity, in some form or another. Many elements need a lot of work to make them into tiles; melting, boxing in acrylic, that sort of thing.

I do have some newly-cut tiles and I will take a new picture soon, but my sulfur tile was broken and I must cast a new one. The last one was terribly thin anyways.

2008-01-20
It has finally gotten very cold the last few days. The inability to work outside has brought a lot of things I want to do to a halt. Cutting graphite for more crucibles and electrodes produces carbon dust of such a fine nature that it is difficult to avoid breathing it in, and after having made only a few cuts I will no longer do so inside. Some lower-melting-temperature elements such as Lead, Cadmium and Selenium are ready to be melted and cast but again I would never do so in an enclosed space and so I must wait. And now that I am focusing on etching for the element symbols but I cannot do that in an enclosed space either because of the noxious vapors produced by the acids. So I am focusing on the drilling of holes in the furnace body and on the woodworking of the table which so far has been an utter failure and can only improve ;)

2008-01-15
Magnesium (cut and in need of a shine), Tin (cast), Sulfur (cast), Copper (cut, sanded and shined up nicely), Bismuth (cast, with annoying holes), Indium (cast), Aluminum (cut), Titanium (cut and in the need of filing) and Carbon (cut graphite)

I am also in the middle of gathering parts for an electric arc furnace.

  • Materials
    • arc welder — got it
    • refractory brick for furnace body — EMI Hard Brick (3000°F) 9. x 4.5. x 2.5 — got it
    • graphite block for the fashioning of the crucible/mold — got it
    • copper-clad graphite electrodes — going to cut from crucible/mold graphite
  • Steps
    • Machine crucible/mold — in progress
    • Machine brick body — in progress

Basic Strategy

OK, there's an enormous amount to be done. I'm not going to worry about about every detail of every tile, because a) I'm still learning and don't know how I'll end up solving many problems and b) because I'd never get started if I did. I'm going to do stuff at my own pace and not worry about anything as silly as a schedule. I'm going to do some basic research, pick a form factor for the tiles and start making them.

Tile Form Factor

I want a size that's big enough to hold in your hand and appreciate the weight of an element. I want to be able to compare the weight of Magnesium and Gold or Tungsten and Gold. Based on some basic research I decided that 1/8" (~3 mm) was a decent thickness without being too thin or too thick and sheets/plates are generally available for that thickness. As for size I originally planned on having tiles 3" (~7.6 cm) square with 1/16" (~1.5 mm) border giving me tiles 2 7/8" (~7.3 cm) square. Anything bigger would be hard to hold in your hand. This seemed like a good size before I seriously considered the more difficult-to-obtain elements. It's easy to get a 3" square of copper, iron or nickel, but almost impossible to get a 3" square of hafnium, scandium, iridium, lutetium; especially considering the fact that I'm a) not rich and b) doing a lot of the work myself. Also I found that the surface area/thickness ratio made the tiles of the more fragile elements of which I was planning to cast tiles (sulfur, silicon, germanium) susceptible to breakage.

Smaller is better

After the realization that 3" square is too large/expensive I explored some other form factors and decided on (2" x 2" x 1/8") or (~5cm x ~5cm x ~3mm). This halves the total mass of the plate material to a more feasible 0.5 inch3 or ~8cm3. This tile size is still big enough to hold in your hand and notice the differences in weight and it's still big enough to engrave the chemical symbols into the tiles (the jury's still out on that one) — while cutting the material cost of the tile by 50%. Also 2" == 5.08cm, which is close enough to 5cm, which is, to me, aesthetically pleasing that they're approximably round on both units of measurement.

Tile Construction

OK, now I have to go and find enough of every element to fill a tile. Not as easy as it sounds, there are a lot of elements. As with any problem, I simplified it by breaking it into several smaller problems.

Study The Periodic Table

A good way to learn the periodic table is to spend some time with it. Find a version you like and read it, poke around. Make your own. Here's mine, color-coded by category:

H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Figure Out What I Can't Do

First I classified which elements were the most difficult to do properly:
  • Radioactive — element samples spontaneously emit radiation; most are very difficult or impossible to obtain (for good reason); these need extra precautions, planning, handling, etc. if I even decide to do them at all.
  • Very Toxic — elements are poisonous to the point where covering them with a layer of lacquer and treating them with respect isn't enough.
  • Invisible Gas (at sealevel and 70°F) — element samples are completely invisible! I could always just have an empty container and say it was a real sample (wouldn't be lying about Nitrogen, Oxygen and Argon anyways ;) but I'd like to make this as authentic as possible. Let's keep these in mind but not really worry about them until later.

H He
Li Be B C N O F Ne
Na Mg Al Si P S Cl Ar
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
Cs Ba Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
Fr Ra Rf Db Sg Bh Hs Mt Ds Rg Uub Uut Uuq Uup Uuh Uus Uuo
La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

All of these elements need special attention of one sort or another. Many of the radioactive elements are not obtainable in any significant quantity, nor are they worth the risk in doing so. But many of these highlighted elements are obtainable, but I'm not even going to worry about them. I'm going to focus on the easier and safer elements.

Quantize Element Properties

OK, now we're leaving the "difficult" elements behind and will focus on the "easy" elements. Let's see how we can classify their properties so we can figure out how to make tiles for them. We'll start with the most major distinctions and work our way to smaller details.

      
Li Be B C        
Na Mg Al Si P S    
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge   Se Br  
Rb Sr Y Zr Nb Mo   Ru Rh Pd Ag Cd In Sn Sb Te I  
  Ba Hf Ta W Re Os Ir Pt Au Hg   Pb Bi      
                                 
La Ce Pr Nd   Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
                             

Tile Production Strategies

OK, now let's figure out some basic categories of tile production based on available element forms, available means of production and available budget. In increasing complexity:

      
Li Be B C        
Na Mg Al Si P S    
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge   Se Br  
Rb Sr Y Zr Nb Mo   Ru Rh Pd Ag Cd In Sn Sb Te I  
  Ba Hf Ta W Re Os Ir Pt Au Hg   Pb Bi      
                                 
La Ce Pr Nd   Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
                             

Now let's research/discuss the above-mentioned methods in detail:

Cut sheet into tile

Many metals are available in sheet or plate form. Actually, let's discuss what "sheet" and "plate" mean, because in industry they have specific meanings. When searching for metal one will see the terms (in terms of increasing thickness) "foil", "sheet" and "plate". But where does one draw the line? Can a thick foil be thicker than a thin sheet? Are there certain thicknesses more or less represented than others? Apparently, there is no overall standard though certain sectors may have their own conventions or standards. Here are some samples of the thicknesses of these forms:
Source Total Thickness
foil sheet plate
aluminum.org
.006"-.249" >.249"
American Elements
.001"-2mm ? .25"-1"
So for our purposes of procuring 1/8" (0.125") thick metal we will generally be looking for sheet and not for foil nor plate.

So of which metals can we find sheet? Ebay's "Metals & Alloys" section lists the following elements:

  • Aluminum
  • Copper
  • Magnesium
  • Iron (as Steel; Steel is Iron with Carbon and possibly other elements added)
  • Titanium
Since these metals have their own categories it is obvious they are relatively common and obtaining them simply means finding a few square inches of sheet of the correct thickness; either on ebay or from a local scrapyard.

That leaves...

  • Carbon — Early on I toyed with the idea of carving up a piece of coal, or using some cubic zirconium as diamonds, but I decided on a sheet of pure Carbon. Carbon is available as sheets of carbon fiber or graphite. Though carbon fiber is a wonderful and extraordinary material I decided to with graphite because it is less adulterated; conveniently it is also less expensive. Graphite is what is inside your pencil and it is used in many high-temperature applications because Carbon's melting point is higher than everything else. Graphite can be obtained in large blocks for making molds, as crucibles or as sheets from a ceramics supply store.
  • Vanadium — Vanadium is used as a steel alloy as a hardener and is not as often used by itself. This will have to come from an element collector. In fact, there is a perfectly-sized piece out there right now, but I can't afford it at the moment.
  • Nickel — Nickel sheet can be found; I'm hoping to find some at a local scrapyard. The Nickel content of 'Nickel 200' alloy is >99%
  • Zirconium — sheet is out there, hope to find on ebay.
  • Niobium — sheet is out there, but it's not exactly the kind of thing you stumble across; Unless you are a world-renowned element collector (off of whom I managed to buy a pre-cut sheet)
  • Tantalum — pure standalone tantalum *is* used for things like evaporation boats because of its high melting point and corrosion resistance coupled with its decent machinability and lighter weight than Tungsten. Unfortunately, one doesn't find a lot of 1/8" sheets of it; however I'm fairly confident I can find this as a scrap from industry instead of from an element collector.
  • Tungsten — I got lucky and found a company named Midwest Tungsten Service who happen to maintain an orphan page of various scrap from their operation. After monitoring it for a few months I ran across some (too thin) tungsten sheets, but the price was right and I bought one.
Cutting Metal
Not many people stock 2"x2" pieces of sheet. Once we get a larger piece what tools can we use to cut it down to size?

In terms of complexity:

Hacksaw
Hacksaws are pretty much the simplest way. No electricity involved, just your arm versus 1/8"-inch thick metal. The upsides are that hacksaws are readily available and cheap; the downside is that it's basically impossible to saw in a perfectly straight line and some metals take a very long time to cut. Due to the imperfection of the line, one must cut a piece slightly larger than required and file straight; this wastes some material and involves extra time and work.

I picked up a "midget hacksaw" and a pack of blades from Home Depot for a few dollars. Now, I know I listed "takes a long time" as a downside, but I can attest that one really starts to learn about metals by cutting through them.

Magnesium, for example, cuts like butter. A tile can be cut out in just a few short minutes and little effort. Aluminum is a bit harder and take a bit longer. Copper is much heavier and takes yet longer.

Titanium is harder still. For metal that doesn't feel much heavier than Aluminum it sure takes a long time to cut through. I now appreciate the featherweight strength of Titanium (the average passenger jet these days contains tons of the stuff).

Tungsten, however, takes the cake. Even my too-thin ~1/16" sheet took ages to cut through. After a while I realized that the tungsten carbide abrasive on the hacksaw blades would wear completely off — it took me about approximately one blade per 3/4" inches (luckily blades are cheap). I have a new appreciation for the toughness of Tungsten. That being said, for all the hardness my thin sheet exhibited it was also very brittle. I haven't managed to cut a decent piece without some of it cracking away. Just goes to show that strength is more than just being hard.

Metal-cutting bandsaw
I would love to get one of these, cheap versions are carried by grizzly and harbor freight. I'm not sure whether I can justify the expense though, and I'm not sure how they will perform on the really tough metals like Tungsten. Bandsaw blades are not so cheap.
Metal cut-off machine
As far as I can tell this is a metal-cutting chopsaw; it is cheap enough to be an option.
Plasma cutter
Plasma cutter is futuristic. Using only a small piece of hafnium and a large amount of electricity one can cut through just about anything. Unfortunately, the $1000+ cost is not within my price range.
Water jet cutter
Waterjets are amazing, they can cut through anything using only a highly-pressurized stream of water (and an abrasize grit). Unfortunately they are huge, complex machines and are outside the realm of the hobbyist. These are also expensive to use and are not a realistic option for me, both because of the cost and the relative simplicity of my needs which can be accomplished by other means.
Laser cutting

Melting and Casting

I need a way to put any element that I can't already buy in sheet form into it.

After some research I discovered the world of amateur metalcasting which basically involves operating a backyard micro-foundry. In a nutshell one builds a small insulated gas-powered blast furnace out of refractory material, melts metal such as aluminum and then pours the molten metal into a cast (generally made of a sand mixture). I went down the road of metalcasting for months, but I realized that it still would fall too short of what I needed — higher temperatures. Home-made gas-and-oxygen-powered furnaces can realistically only melt Iron around 1535°C. It would only work for a small set of medium-melting-point elements; I wouldn't even get the benefit of the classic metalcasting elements of Lead, Aluminum or Iron because those are more easily available by other means. So I put a blast furnace on the *ahem* back burner. How could I hope to obtain temperatures at and above 2000°C?

The answer is an electric arc furnace. An EAF cuts right to the chase; instead of heating stuff up and then exposing the metal to it, we simply run high amps/low volts directly through the sample until it melts. And it will melt. More on EAFs soon, I am doing research on them.

The Electric Arc Furnace
The electric arc was discovered at the beginning of the nineteenth century and electric arc furnaces were developed not long after. However, it was only after the invention of the dynamo (electrical generator) that they became practical, as large banks of batteries were costly sources of electricity. In the 1890s French chemist Henri Moissan designed a furnace capable of melting large amounts of Tungsten (melting point 3410°C/6170°F). The furnaces were small, measuring less than 25cm/10" on the largest side. All shared the following basic design:
A small graphite crucible sat within a cavity inside blocks of refractory quicklime (calcium oxide). Graphite electrodes were inserted so as to touch a short distance above the crucible. When electric current was run through the electrodes a small arc could be struck which heated the surrounding air, crucible and load. The quicklime, a very poor conductor with very high melting point acted as refractory, containing the heated elements inside.

Mr. Moissan was interested in researching the volitalization (vaporization) of elements and the development of high-temperature compounds (carbides, silicides, etc.). He was especially interested in discovering a way to convert carbon's other forms into diamond (which failed). As such he was always striving for the highest temperatures possible. His later furnaces used large amounts of electricity (1000 amps at 60 volts); so much electricity that his experiments' thirst for electricity outstripped the most powerful standalone generators of the day and his later experiments drew directly on a city power plant.

I, however, am not interested in vaporizing any metal, in fact, I'm hoping to vaporize as little as possible. I just want to melt a few ounces of some exotic metals for the purpose of reshaping them into a tile. As such I will be using much less electricity than Mr. Moissan.

Theodore Gray discussed electric arc furnaces in his Popular Science column entitled "Melting the Unmeltable". One hundred years after Moissan's experiments technology has made significant advances, and yet Moissan's design still holds. Here is a photo of Mr. Gray's furnace:

The only significant difference in design is a viewport which allows us to determine when metal is molten (and thus when we can turn the furnace off). Gray has used it to melt Tungsten.

I have started Issues:

Box Them Up

It is easy to forget we're living in an atmosphere of 78% Nitrogen, 21% Oxygen and a mix of various other materials including water vapor. Some elements need protection from the very air itself. All of the Alkali Metals and most of the Alkali Earth Metals fall into this category. Also Mercury, Phosphorus, Bromine and Iodine need containment for their own reasons. So what are my options for containment? I need a box that is roughly 2"x2"x1/8".

Here are my requirements for the boxes and their material:

Translucent
Material must allow light in so the elements can be seen(!)
Non-reactive
Material must obviously be inert as far as reacting with the elements I am containing.
Airtight
I made a test cube using 1/8" thick acrylic sealed with epoxy glue. The box is filled with water. The water will not leak out of the box, but it does slowly evaporate, meaning that it is not airtight. Need to do better than that.
Small
The box should be 2" x 2" and between 1/8" and 1" tall, no more. This is the form factor I have chosen.
Tough
If it is dropped it needs to not break. Scratching upon a drop would be an acceptable concession, simply because safety is very important and at worst we could always get another (less scratched) box, and it would likely be cheaper than a new element.
As far as I know we have basically 2 choices: glass or plastic. Silicon Dioxide or Acrylic.

Other Tile Issues

Chemical Element Symbols

I would very much like to mark the element tiles with their respective chemical element symbols ("Au", "Si", etc.). That would be the finishing touch, making the tile represent itself completely. There are other possibilities, such as reverse-etching the periodic table on glass above the tiles, or carving the symbol into the wood below. But I want people to be able to pick up a tile, feel its weight, see it's color and texture and know unequivocally what it is.

At first I thought engraving (mechanical cutting) would be the obvious way to form the chemical element symbol on the plates, however this is harder than it sounds. The wide variety of materials, the large difference in hardness and the external reliance on a CNC mill or similar type machine made me put this off.

Use chemicals. It is much more interesting. All you have to do is buy a manual battery charger (40$) if you don't have one, HF HCl HNO3 and NaOH. Total of about 140$. With it you will get excellent results in etching. — PK
I have since looked into the field of etching and it seems promising... artists have been making fine lines in metal by chemical means for a long time and it seems to work well. So now I am focused on etching.

Polishing/Finishing Metal Tiles

Once a metal tile has been casted or cut we need to ensure its proportions are correct and then polish it to a nice shiny finish. In approximate order I use:
File
Mostly for deburring the cut edges, though I have experimented using the file directly on the face of harder metals.
Sandpaper
I work my way from large to finer grits from 220, 400, 600 (wet) and finally 1000 grit (wet).
Polish Solutions
I will try to review the effectiveness of different products
Buffing Compounds and a Buffing Wheel
I bought a kit with some buffing wheels and jeweler's rouge, so far it hasn't produced superior results to sandpaper, so that probably means I'm doing something wrong.
Bench Grinder
I haven't tried this yet, but we have one at work that I might try.

Research Links