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 10

Just one more set of facts after this one!

• The radioactive element actinium (Ac, #89) really does glow in the dark!
• Darmstadtium (Ds, #110) actually has a nickname. In Germany, where it was discovered, the emergency telephone number is 110 (not 911, as in the U.S.). Since Ds is element #110, it is sometimes jokingly called policium.
• Sometimes people worry about getting too much sodium (Na, #11) in their diets. But some sodium is essential to good health, because it helps send signals through your nerves.
• Rubies get their beautiful red color from chromium (Cr, #24).
• Metal objects that are going to be used outdoors are often galvanized, or coated with zinc (Zn, #30), which does not rust.
• Promethium (Pm, #61) has been detected in the stars of the Andromeda galaxy.
• Many laundry bleaches contain chlorine (Cl, #17). These are the bleaches that cannot safely be used on colored fabrics.
• Scientists have found rocks that contain a lot of manganese (Mn, #25) on the ocean floor. No one knows how they formed!
• In the future, rubidium (Rb, #37) might be used to make a new type of battery.
• Terbium (Tb, #65) is one of four elements that are named after the small town of Ytterby, Sweden. In the 1800's, rocks from that area were found to contain four unknown elements - ytterbium, yttrium, erbium, and terbium.

Copper Coating

Many metal objects around you are plated - they have only a thin coating of the metal you see covering another metal (usually less expensive). In particular, a lot of things are gold-plated or silver-plated. Gold and silver cost too much to experiment with, but here's an easy way to copper-plate a nail.

What you'll need:
1/4 cup (50 mL) of lemon juice or vinegar
Plastic or paper cup
10 to 20 dull pennies
Salt
2 small iron nails (not the galanized kind)
Steel wool scouring pad

Pour the lemon juice into the cup and drop the pennies in. Add a pinch of salt. What do you see happening? Wait three minutes. While you're waiting, scrub one of the nails with the scouring pad to clean off the surface. Rinse the nail well. Just put the second nail off to the side. Drop the cleaned nail into the cup, and wait about an hour. After that time has passed, take the nail out and compare it to the one you set aside. What do you see? When you're done, make sure to pour the lemon juice or vinegar down the drain and to throw the cup away.

As you may know, pennies are coated with the element copper (Cu). When you dropped them into the lemon juice or vinegar, bubbles formed. Metals like copper often react with acids (like the citric acid in lemons or the acetic acid in vinegar) to form bubbles of hydrogen (another element!) gas. You may have noticed that this solution changed color as some of the copper dissolved. When you added the iron (yes, yet another element!) nail, the dissolved copper collected on its surface, giving the nail a brown coat of copper.

The instructions said that you should not use a galvanized nail (which is coated with zinc - these elements are everywhere!), but you might want to try one, just to see what happens!