What're Materials?

Major Categories:

	Metals Whole periods of human civilization - such as the Bronze and Iron ages - are named for metals. These were the first materials to be "engineered," that is, people changed them to fit what they needed to do, rather than just letting their natural properties determine what they could be used for. These days, materials scientists are using metals in ways no one could have pictured even a few years ago - for example, shaping copper into tiny wires a thousand times skinnier than a strand of your hair!
	Ceramics Think about a china teapot - that's one type of ceramic. But ceramics can also be used to create bone and tooth replacements, super-strong cutting tools, or to conduct electricity. With the addition of oxygen or nitrogen, metals become ceramics, too.
	Semiconductors One of these materials - silicon - is making it possible for you to read these words right now! That's because silicon is the essential material in an electronic computer chip. "Semiconductor" means a material can conduct electricity with a bit of help in the form of added "impurities." Your CD, DVD player, and telephone - all depend on semiconductors.
	Polymers Polymers are just very big molecules made of smaller molecules linked together into long, repeating chains. You may not know it, but you're in touch with polymers every day more than any other kind of material. Rubber bands are made of polymers, so are paints and every kind of plastic. And by the way, most of the food you eat is made of natural polymers!