The elements in the periodic table are the ingredients that make up our world. Explore elements such as carbon, oxygen, and hydrogen, and learn why they are essential to our survival. See how precious gold protects astronauts in space, and why the metal mercury can be both a solid and a liquid. Find out about man-made elements, which the smartest chemists are busy figuring out how to use. Learn about scores of other elements, including silver, the alkaline earth metals, the nitrogen elements, and the noble gases, such as helium and krypton.