LanthanumK's Blog

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

Tellurium is a brittle, semimetallic element in the chalcogen group. It is one of the rarest elements in the earth's crust. Tellurium is quite unreactive and does not dissolve in acids. Tellurium forms hexavalent covalent compounds such as the hexafluoride, which are quite low melting and reactive. Tellurites and tellurates, however, are the more commonly used tellurium compounds, as the alkali metal salts are water soluble. Tellurium occurs in the anode sludge when copper is refined, as well as in some selenium minerals. When tellurium is metabolized in the human body, it produces ethyl telluride, which smells very strongly of garlic.

In element form: Tellurium copper, a rare alloy of copper, contains about 0.5% tellurium. Tellurium is used in some old photocopiers instead of selenium.

In compound form: Tellurium suboxide is used in rewritable CDs and DVDs. Thermoelectric heaters (peltier plates) use lead or bismuth telluride as the semiconductor to produce the hot and the cold sides.

Here is my sample of tellurium. It is a DVD-RW.

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

Antimony is a bluish-gray brittle semimetal. It is insoluble in non-oxidizing acids, but dissolves in oxidizing acids. It burns in air with a bluish flame to produce white antimony trioxide. Antimony is quite toxic, though not as toxic as arsenic. Antimony is found in the earth as stibnite, an antimony sulfide mineral. This is reacted with scrap iron to make antimony metal. When antimony is precipitated from solution, it is a black powder like many metals when precipitated. Antimony strengthens lead and tin alloys.

In element form: Stibnite can be dissolved in concentrated hydrochloric acid and reacted with zinc metal to precipitate amorphous antimony metal. Antimony-tin alloys can be dissolved in HCl, leaving antimony behind. Most lead-acid batteries have antimony alloyed in their electrodes. Pewters generally contain antimony.

In compound form: Some match heads have antimony trisulfide in them.

Here is my sample of antimony. It is powder produced from a pewter alloy in hydrochloric acid.

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

Tin is a soft, whitish-gray metal in the carbon group. Tin is moderately reactive and quite resistant to corrosion by air or water. It dissolves slowly in hydrochloric acid, forming a colorless solution of tin(II) chloride. Tin(II) chloride is a reducing agent, capable of reducing copper(II) chloride to copper(I) chloride, for instance. Tin also forms a tetravalent state, which is predominantly covalent. Cassiterite, composed primarily of tin dioxide, is tin's primary ore. Tin forms two allotropes, one of which (beta tin) is shiny, soft, and metallic; the other, alpha tin, is grayish, dull, brittle, and nonmetallic. Addition of elements like antimony prevents the change of beta to alpha at cold temperatures. Tin's compounds are mostly colorless but its iodides are bright red or orange.

In element form: Galinstan, found in Geratherm mercury-free fever thermometers, contains about 10% tin. Tin-lead solders contain about 60% tin. Most common lead-free solders are about 98% tin. Electrolytic oxidation and then reduction of any tin alloy produces pure tin at the cathode. Bronze contains tin.

In compound form: Indium tin oxide is used as a transparent electrode in LCD screens. Tin dioxide is also used in many ceramics.

Here is my sample of tin. It is electrolytically purified powdered tin from a pewter object.

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

Indium is an extremely soft, silver-gray metal. It is found under aluminium in the post-transition metal area. Indium is moderatley reactive and dissolves with ease in strong acids. Its oxide is amphoteric, meaning that it is soluble in both acids and bases. Indium compounds are colorless or white and acidic, making them uninteresting. Indium metal, however, is extremely malleable and retains this characteristic to cryogenic temperatures. Indium can be used to seal gaps because of its tendency to stick to other metals, acting like a superior form of paraffin wax. Indium metal is quite expensive, with a current price of about 250 USD per pound.

In element form: Galinstan, a liquid metal alloy used in Geratherm mercury-free fever thermometers, contains about 32% indium. Indium is often used in specialty solders. Field's metal, used in some low-melting seals for fire sprinkler systems, contains indium. The brass pin in the center of AA or AAA alkaline batteries is often plated with indium to prevent the zinc from passivation.

In compound form: LCD screens use indium tin oxide (90% indium oxide) for transparent electrodes. Indium is found in most LEDs.

Here is my sample of indium. It is a piece of pure indium metal from GalliumSource LLC. This is only a small piece, flattened to a foil by gentle pressure.

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

Cadmium is a soft, blue-gray metal that is considered borderline between the transition metals and the post-transition metals. Like the post-transition metals, it forms primarily one oxidation state, its compounds are generally (although not completely) colorless, and it is soft and low-melting. However, it is in the d-block, so it is technically a transition metal. Cadmium is toxic and replaces zinc as a heavy metal poison. Cadmium is moderately reactive (more so than mercury but less so than zinc), so it dissolves easily in hydrochloric acid, forming hydrogen and a colorless solution. Cadmium sulfide, however, is bright yellow. The oxide can be brown (the other form is white), and the selenide is red. There are few other colored cadmium compounds.

In element form: Nickel-cadmium batteries supposedly contain cadmium metal at the anode, but I have never been successful in extracting any cadmium from a "sub-C" cell battery. Little rechargeable button cells (LR1130) contain a gray paste at the anode that is probably cadmium metal mixed with a binder. Cadmium plated bolts and screws used to be relatively common, and can be distinguished from zinc by the increased softness of the coating.

In compound form: Cadmium sulfide was used in cadmium yellow pigment, but has been almost completely discontinued due to toxicity. Cadmium sulfide is still used in photodetectors as the orange line separating the two electrodes because of its change in conductivity due to light.

Here is my sample of cadmium. It is a cadmium plated screw, found amongst hundreds of other screws by scratching the coating with magnesium metal. Cadmium plating typically has the dull bluish-gray appearance, somewhat like hot-dipped galvanized zinc. This is probably due to aerial oxidation.