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Metals are the backbone of modern civilization. In this high-interest video, we learn about the history of precious materials such as gold, copper, iron, and aluminum. This video is one of the three part series NOVA: Treasures of the Earth: Gems, Metals, Power.
Gold has been valued since antiquity. It is the best metal for jewelry making, and it never tarnishes. Gold from the tombs of Egyptian pharaohs is just as beautiful today as when it was first made. Today we know that gold and other heavy metals are the gifts of exploding stars, supernovas, that erupted before earth had even formed. Scientists are working on sending gold back into space in the form of the James Webb Space Telescope, the successor to the enormously productive Hubble Space Telescope. A few ounces of gold will be used to form the surfaces of the segmented mirror in the new telescope. Gold is able to reflect nearly 100% of the infrared energy striking its surface, so it will enable the James Webb Telescope to see into the infrared universe and make new discoveries in this realm of light invisible to the human eye.
Copper is an important metal. Today, we rely upon it to carry electricity. Metals have the extremely useful property of conductivity. At the atomic level, metals present a “sea” of freely moving electrons. This feature allows the unique properties of metal such as malleability and ductility, as well as allowing the conductance of heat and electricity. Copper also possesses an antibacterial ability-it kills surface bacteria, and it may be useful in hospitals as a replacement for stainless steel in order to limit the spread of “superbugs” on hospital surfaces.
Tin added to copper allowed our ancestors to make metal tools such as swords and plows. Early bronze weapons are found in abundance. One noteworthy discovery discussed in the video is the Sword of Goujian. Discovered in Chinese tomb, this sword was in pristine condition and still bore an edge as sharp as a razor. The discovery of alloys, mixtures of metals, eventually led to the development of the most important alloy we have, steel, which enabled the construction of “high and strong” structures such as bridges and skyscrapers. Architectural marvels such as the Beijing “Birdnest” National Stadium, and the Millau Viaduct in France, the world’s tallest bridge, all rely upon special alloys of steel, and are discussed in the video. In the more recent past, iconic structures such as the Eiffel Tower and Chicago’s Home Insurance building, the world’s first skyscraper, were constructed of wrought iron and steel respectively.
The future of metals is discussed with the use of landfill trash as a source of carbon for the manufacture of “green steel”, which will help eliminate excess trash and require less fossil fuel usage in its manufacture, helping to alleviate the introduction of excess carbon dioxide into earth’s atmosphere, the main culprit behind the modern crisis of global warming. The video also introduces the viewer to scientists who create “metal foam”, a flexible metal that may be useful in the engineering of structures that can move, grow, and repair themselves, rather like the metal-man Terminator from the movies. The video also discusses graphene, a carbon-based material of incredible strength, which can be used as a metal-like material.
The zip file download contains a two-sided video worksheet consisting of 54 multiple choice and true-or-false questions, along with an answer key. Files are provided in both MS Word and PDF formats. You will need to obtain a DVD of the video, use the PBS Internet site, or YouTube.