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May 7 2012 2 07 /05 /May /2012 12:51

I have compiled a list of sources for the elements that are available to the amateur chemist. Iridium will be discussed here.

 

Iridium is one of the rarest and densest elements in the earth's crust. It is found in small concentrations in platinum ores and competes with osmium for position of densest element, the two's densities being extremely close (22.56 grams per cubic centimeter for iridium, compared with 22.59 for osmium). Iridium's is named after the "goddess of the rainbow" because of the many colors that it exhibits in its salts. Meteorites tend to contain larger quantities of iridium than the general earth. Iridium does not dissolve in any acids, but is attacked by halogens and some molten salts when heated to a high temperature. Iridium black is an extremely black pigment for ceramics made of finely divided iridium metal. See this link for more information about the colorfulness of iridium chloride and its complexes.

 

In element form: Iridium spark plugs often contain pure iridium or iridium-platinum alloys plated on the central electrodes. Osmiridium pen tips for expensive pens contain iridium metal.

 

In compound form: No sources found.

 

Here is my sample of iridium. It is a spark plug with the electrode coated with a platinum-iridium alloy (90% Pt 10% Ir is typical).

 

 

Iridium.JPG

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May 5 2012 7 05 /05 /May /2012 12:38

I have compiled a list of sources for the elements that are available to the amateur chemist. Osmium will be discussed here. 

 

Osmium is an interesting element. It is named after osme, which means stink. This refers to the tendency of powdered osmium to oxidize in air to form colorless, volatile, smelly, and highly toxic osmium tetroxide. Osmium itself is the densest element on the periodic table and one of the few colorful metals; it is light bluish, shiny, and brittle. Osmium is quite inert in bulk form but in powdered form it is quite reactive. It was discovered from platinum ores in the 1800s.

 

In element form: Some old photographic needles were supposedly made of osmium. Fountain pen nibs were sometimes made of osmiridium ore.

 

In compound form: No sources found.

 

I do not have any osmium at the time of this writing.

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May 4 2012 6 04 /05 /May /2012 12:56

I have compiled a list of sources for the elements that are available to the amateur chemist. Rhenium will be discussed here.

 

Rhenium was the last non-radioactive element discovered. The metal itself is extremely dense and lustrous. Rhenium has the highest boiling point of any metal. Rhenium forms perrhenate compounds, which are the most commonly traded form of rhenium. These are much weaker oxidizing agents than the permanganates. Rhenium metal is made by heating the ammonium perrhenate. The rhenium powder is then sintered to form the desirable shape. Rhenium is one of the rarest elements in the earth's crust, with an average concentration of 1 milligram per metric ton in the earth's crust. Rhenium forms a wide variety of colorful and not well-defined compounds in many oxidation states.

 

In element form: Some thermocouples have tungsten/rhenium alloy in them. Antique GE rhenium flashbulbs have a tungsten/rhenium alloy filament used to trigger the flash.

 

In compound form: No sources found.

 

I do not have any rhenium collected at the time of this writing.

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May 3 2012 5 03 /05 /May /2012 17:43

I have compiled a list of sources for the elements that are available to the amateur chemist. Tungsten will be discussed here.

 

Tungsten comes from the name "tung sten", which means "heavy stone" in Swedish. Tungsten, true to its name, is a dense, gray metal of Group 6. Tungsten, when pure, is quite flexible, but becomes brittle from impurities. It is quite inert at room temperature to most acids and alkalis. However, it burns when heated, forming the yellow-green compound tungsten trioxide. This is why the filament in an incandescent bulb must be protected from oxygen by filling the bulb with argon and nitrogen. Tungsten forms colorless tungstates, which precipitate the hydrated trioxide upon acidification. Tungsten is found as calcium tungstate, which is acified to precipitate tungsten trioxide and reduced with hydrogen to form tungsten powder. This is sintered into various shapes. Tungsten hexafluoride, a highly corrosive substance, is the heaviest known gas.

 

In element form: Open an incandescent or halogen bulb (the higher wattage the better) and remove the tungsten filament. Tungsten is used in rod form in TIG (tungsten inert gas) welding.

 

In compound form: When a tungsten filament is burned in air, it produces yellowish tungsten trioxide. Tungsten carbide is both used in jewelry and as an abrasive for blades and grout cutters.

 

Here is my sample of tungsten. It is a filament from a 500 watt halogen lamp. This is a significant amount of tungsten.

 

Tungsten-ring.JPG

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May 2 2012 4 02 /05 /May /2012 13:26

I have compiled a list of sources for the elements that are available to the amateur chemist. Tantalum will be discussed here.

 

Tantalum is an extremely dense, bluish-gray metal. It is named after the king Tantalus, who was submerged in water he could not ever drink and was near fruit he could never eat. Tantalum's behavior of being submerged in acids but never able to dissolve was the reason that it was given the name. Tantalum is a rare and expensive metal, found in niobium ores. It was mistakenly confused with niobium, despite its much higher density, and is difficult to remove from the aforementioned metal. When tantalum is pure, it has excellent physical strength and properties, making it ideal for artificial limbs and fine medical instruments. Tantalum, despite its seeming invincibility, has its weak points; it can be dissolved in hydrofluoric acid or molten hydroxides. Tantalum is primarily pentavalent, which is part of the reason for its inertness. The oxide is a white unreactive substance, difficult to reduce to the metal. It can be made to form compounds to dissolving in molten metal hydroxides or electric arc fusion with other metals, forming a range of tantalates. 

 

In element form: High capacity (30 mfd or so) tantalum capacitors have a lump of anodized tantalum in the middle. Use hot hydrochloric acid to dissolve any manganese dioxide which may be present. Some expensive medical instruments use tantalum.

 

In compound form: Motion sensors may contain lithium tantalate as the sensing material.

 

Here is my sample of tantalum. It is a nugget of tantalum metal with tantalum connector wire, taken from a 22 mfd tantalum capacitor. The green anodized color is visible in certain places.

 

Tantalum-capacitor-core.JPG

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May 1 2012 3 01 /05 /May /2012 13:15

I have compiled a list of sources for the elements that are available to the amateur chemist. Hafnium will be discussed here.

 

Hafnium is the first element after the long and boring series of rare earth metals are completed. (Whether you wish to purchase all of them is a matter of your decision, of course, but some of the very similar ones may be skipped.) Anyway, hafnium is a dense (more so than lead), silvery gray transition metal. It absorbs neutrons, making it a harmful impurity in zirconium nuclear fuel casings which must allow the radiation to escape. Therefore, many pains are taken to remove hafnium from zirconium. In most applications, however, most zirconium is mixed with hafnium and vice versa. Therefore, your cubic zirconia is probably also cubic hafnia. Hafnium forms rather low-melting tetravalent compounds; its chloride hydrolyzes in water to form an insoluble hafnium oxychloride, just like most tetravalent compounds. Hafnium is extremely corrosion resistant and does not dissolve in acids or bases. It can burn in air when finely powdered, though, just like titanium. Hafnium finds use in very high-melting alloys, such as those used in rocket nozzles.

 

In element form: Find a plasma cutter tip at a welding shop and cut off the copper end. You will see a small cylinder of hafnium metal in the center.

 

In compound form: Cubic zirconia undoubtedly contains some hafnium, as well as most other sources of zirconium.

 

Here is my sample of hafnium. It is a plasma cutter tip tip.

 

Hafnium.JPG

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April 30 2012 2 30 /04 /April /2012 13:03

I have compiled a list of sources for the elements that are available to the amateur chemist. Thulium, ytterbium, and

lutetium will be discussed here. 

 

Thulium is a typical rare earth metal. Its compounds are pale green to yellow. No sources of it are available to the general public.

 

Ytterbium is another rare earth metal. Its liquid range from 824-1196 C is the smallest of all metals. Most ytterbium compounds are white and boring. It does form divalent compounds, however, of which the chloride is green. Earthquake meters may contain ytterbium metal to measure the quake, but it is unlikely that they do.

 

Lutetium is the last of the rare earth metals. It is the rarest and most expensive one. Its compounds are boring and white. Lutetium tantalate is the densest white substance besides thorium dioxide, which is slightly radioactive. There  are no household sources.

 

Here ends the sequence of little articles about rare earth metals.

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April 28 2012 7 28 /04 /April /2012 13:18

I have compiled a list of sources for the elements that are available to the amateur chemist. Erbium will be discussed here.

 

Erbium is a typical not-so-reactive rare earth metal. Erbium forms pink compounds that fluoresce in UV light. It is solely trivalent. These heavy rare earth metals are quite boring as they are so similar to each other.

 

In element form: No sources found.

 

In compound form: Some glass is colored pink by the addition of erbium oxide.

 

I do not have any erbium at the time of this writing.

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April 27 2012 6 27 /04 /April /2012 13:11

I have compiled a list of sources for the elements that are available to the amateur chemist. Holmium will be discussed here. 

 

Holmium is one of the less reactive rare earth metals. It forms a yellow trivalent solution when dissolved in acids. Holmium(III) oxide has a color that changes depending on the light source. In normal light it is a dull yellow, while in trichromatic light it is bright pink.

 

In element form: No sources found.

 

In compound form: Commercial calibrators for spectrophotometers use holmium oxide glass or in some cases a holmium oxide solution.

 

I do not have any holmium or holmium compounds at the time of this writing.

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April 26 2012 5 26 /04 /April /2012 13:09

I have compiled a list of sources for the elements that are available to the amateur chemist. Dysprosium will be discussed here.

 

Dysprosium is one of the less reactive rare earth metals. Its compounds are trivalent and generally colorless, although the soluble compounds supposedly have a yellow solution. Dysprosium is quite a boring rare earth metal.

 

In element form: Dysprosium alloys are used on many hard disk platters. Terfenol-D, the alloy in a Soundbug(r), contains dysprosium metal.

 

In compound form: No sources found.

 

Here is my sample of dysprosium. It is a hard disk platter.

 

Dysprosium.jpg

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