Reader Question – Eduardo Wolfart Aveline, São Paulo, SP
Tungsten
Melting temperature – 3,422 oC
Market value – US$ 0.40 a kg
Use It is used in the manufacture of high-speed steel, the material used to coat aircraft engines. Another application is in drills and drilling tools in the oil industry. But you might recognize it from the filament of incandescent light bulbs.
Copper
Melting temperature – 1,085 oC
Market value – US$ 7.15 a kg
Usage Used as an electrical conductor in gadgets. It is also a decorative element, and covers the outside of the Statue of Liberty. Can be used in pans, although they are prohibited because they release toxic residues into food
Silver
Melting temperature – 960 oC
Market value – US$ 615 a kg
Usage Like gold, it can be used in jewelry and cutlery. It is also the reflective material behind mirrors. It also has medical use, both for the treatment of some cancers and in the manufacture of certain surgical instruments. It’s also great against werewolves!
Mercury
Melting temperature – -38 oC
Market value – US$ 140 a kg
Usage Thermometers, barometers and other measuring instruments use the element. The biggest application of mercury during the 20th century, however, was in the manufacture of caustic soda. It is one of the few liquid metals at room temperature.
Platinum
Melting temperature – 1,768 oC
Market value – US$ 44 thousand per kg
Usage Dental implants, orthopedic prostheses, weapons and projectiles use the element. Very resistant to acids and very malleable, it has a grayish white color. The name is a diminutive of “silver”, a metal with similar characteristics.
Gold
Melting temperature – 1,063 oC
Market value – US$ 39 thousand per kg
Use Widely used in the making of jewelry. As it reflects infrared light well, it coats satellites to protect them from the sun. Some cable connectors (headphone or HDMI) are gold plated to retard oxidation
metallic alloys
WHITE CHOLOCATE BONBON
Melting between 943°C and 1,079oC
Mixture of 50% to 90% gold and at least one other metal such as manganese, palladium or nickel
BRONZE
Melting between 900°C and 1,000°C
Alloy consisting of copper (generally more than 65%), tin and other elements
BRASS
Melting temperature between 880°C and 980°C
Composed of copper and zinc, but may contain other metals such as lead
CONSULTANCY: Lúcio Angnes, professor at the USP Chemistry Institute, and Larissa Delissa, nanotechnology advisor at the Catavento science museum