Alloys

An alloy is a mixture of two or more elements, at least one of which is a metal.  Most metallic items are actually made of alloys, not metals.  They are usually prepared by melting a mixture of the ingredients and then cooling them to form a solid.  Subsitutional alloys are when the atoms of the atoms of the different elements are about the same size and so they replace each other in the crystal.  Interstitial allotys are formed when the atomic sizes are different and the smaller one fits into the spaces in between the larger atoms.  One example of an alloy is brass, which is made up of copper and zinc.  Another is steel, which there are many types of, in some of which there is carbon and iron.