Liquid Metals

You may know that metals will melt if you get them hot enough, and may have seen pictures of molten steel being formed into useful objects. Do you know how how steel is? It's about 2500^oF (1370^oC)! Yikes, that's hot! But steel is nowhere near being the highest-melting metal. That distinction goes to tungsten (6200^oF or 3400^oC).

OK, so what's the lowest-melting metal? You may know the answer to this. It's a liquid, silvery metal that is sometimes used in thermometers - mercury! It's not so common to find mercury thermometers today. This metal is very poisonous, so people avoid using it whenever possible. Most thermometers now use a kind of alcohol (usually a red or green liquid) instead. But this is beside the point - what is mercury's melting point? Brrr... it's a chilly -40^oF, which oddly enough, happens to also be -40^oC. But there's another metal, called gallium, that would liquefy on a warm enough day. Its melting point is 86^oF (30^oC). The photo above shows a small sample of gallium actually melting in Dr. B's hand!

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?