Steel Away!

One of the most common metals used in today's world is steel. Steel is mostly iron, but it also contains other elements. As we've already seen, this kind of metal mixture is called an alloy. Most steel contains carbon in addition to iron. Stainless steel also has some chromium, and it doesn't rust. Other types include elements such as molybdenum, vanadium, tungsten, nickel, silicon, manganese, or boron. Different types of steel are used for different purposes. Some are good at high temperatures; others are hard and good at cutting.

The next time you're in a hardware or home-improvement store, take a look at the tools. How many different kinds of steel can you find?

All About Alloys

There are some familiar metals that are actually mixtures of several different types of metals - they are called alloys (AL-oise). Here are a few you've probably heard of (and some that are likely new to you):

• Steel: mixture of iron and one or more other metals (there will be a separate post about steel later)
• Brass (copper and zinc): a shiny yellow metal that looks a little like gold
• Bronze (copper and tin): a dark gold to brown metal that gets darker in color as it ages
• Pewter (copper, tin, and lead): a dark gray metal used for bowls, flatware, jewelry and other decorative items
• Solder (lead and usually tin): an alloy that melts at a relatively low temperature; used to make electrical circuits
• Nitinol (nickel and titanium): this alloy remembers its original shape; used to make eyeglass frames
• Electrum (gold and silver): also known as white gold; used in jewelry
• Alnico (aluminum, nickel, and copper): used to make magnets
• Amalgam (silver, tin, copper, zinc, and mercury): a soft alloy that has been used to fill dental cavities
• Nichrome (nickel and chromium): an alloy that glows orange-red and gives off heat when an electrical current is passed through it; used in toasters and electric burners

Take a look around your house and see how many examples of alloys you can find!

Fun Facts 8

Rolling along...

• A little while ago, we discussed the Periodic Table. Dmitri Mendeleev, a Russian chemist, is the person who is most responsible for the modern Periodic Table, so an element was named in his honor: mendelevium (Md, #101)
• Welders and glassblowers, who work with very bright flames, wear special protective goggles made with didymium glass, which contains praseodymium (Pr, #59)
• Holmium (Ho, #67) oxide has the odd property of appearing light brown in natural light, but red under fluorescent light!
• Toothpaste often contains fluorine (F, #9) because it makes the surface of teeth stronger and more resistant to tooth decay.
• Regular incandescent light bulbs are filled with argon (Ar, #18) gas which helps the filament last longer.
• You might expect that the U.S. nickel (5-cent) coin is made out of nickel (Ni, #28). Actually, it's only 25% Ni (the rest is copper, Cu).
• Many antiperspirants contain a zirconium (Zr, #40) compound that absorbs moisture.
• You may have seen those glasses that change from clear indoors to dark gray outside. They're known as photochromic or photo-gray glasses. Did you know that the color change is due to the presence of silver (Ag, #47) in the lenses? Light causes silver chloride (AgCl), which is clear, to turn into silver metal (Ag), which looks dark.
• Rock layers near the K-T boundary, which corresponds to the disappearance of dinosaurs, is unusally rich in iridium (Ir, #77). Since Ir is more common in meteorites than on earth, scientists believe that the impact of a large meteorite is at least partially responsible for dinosaur extinction.
• Plutonium (Pu, #94) is a very dangerous radioactive element. However, it is used to supply power to spacecraft.