Although you may not realize it, you are already familiar with several elements. For example, the element carbon is in diamonds, used for jewelry, and in graphite, used in pencil lead. We also use the elements gold and silver for jewelry. We need the element oxygen in the air we breathe. We worry about the carbon dioxide emitted by our cars.
Carbon dioxide is a compound , or a combination of two or more elements.
In the case of carbon dioxide, two atoms of oxygen combine with one atom of carbon. Another common compound, table salt, is made of the elements sodium and chlorine. Eight elements combine to make most minerals and rocks found in the Earth's crust. The elements are oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium. The letters in the parentheses are abbreviations.