There are 17 rare earth elements on the periodic table, but a better name for them would be the "troublesome earths." Here's why. When you purchase through links on our site, we may earn an ...

A compound is a pure substance that is made from more than one element. In a compound, elements are chemically bonded together, which makes it very difficult to separate them. When a compound is ...

Many pure metals are too soft for many uses. They can be made harder by adding another element to the pure metal, so forming an alloy. This explains why an alloy often has more uses than the pure ...