Elements: There are 100 known elements organized by similar properties in the Periodic Table. Elements are the building blocks that make all things on Earth. They are the simplest pure substances. For instance, a piece of pure silver has only silver in it. You cannot break it apart into other substances. The symbols for elements (C for carbon) are capitalized. Elements with 2 letters for their symbol (He for helium) always have the second letter in lower case.
Chemistry: The study of how elements interact with each other. Using the Periodic Table, chemists can tell if one element will interact with another, the amount of each element needed for the reaction, and what will happen when they mix. When substances react chemically, one or more new substances are produced.
Alloy: A mixture of metal (while melted) with one or more other substance to improve its properties. Gold jewelry is a mixture of gold and copper to make it stronger (24 carat gold is pure gold and very soft – it also has a very dark yellow color). Zinc + Copper makes Brass. Iron + Chromium makes Stainless Steel. Iron + Carbon makes Steel.