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Elements are the things that make up everything in the world. Every element contains only one kind of atom. (Atoms are tiny bits of matter.) For example, carbon and hydrogen are two of the elements that make up the human body. All carbon atoms are alike. All hydrogen atoms are alike. But carbon atoms differ from hydrogen atoms. There are about 110 elements, and each has its own kind of atom.
Image to right: Information about cobalt atoms is listed in the periodic table. Credit: World Book illustration by James Teason
Elements can join with one another to form a compound. The compound may be very different from the elements that make it up. For example, the elements hydrogen and oxygen are both gases at normal temperatures. But their atoms join to form water -- a liquid. Most elements are found in the form of compounds.
Elements have symbols and numbers as well as names. A symbol is like an abbreviation. The symbol for oxygen is O and the symbol for hydrogen is H. FE, the symbol for iron, comes from ferrum, the Latin word for iron. An element's number, called its atomic number, tells something about its atom. Hydrogen's number is 1, because a hydrogen atom contains 1 proton. A proton is a piece of matter found within every atom. Oxygen's atom has 8 protons, so its number is 8.
Scientists have created a chart that shows the elements with their symbols, numbers, and other information. This chart is called the periodic chart.
How to cite this article: To cite this article, World Book recommends the following format: "Element." The World Book Student Discovery Encyclopedia. Chicago: World Book, Inc., 2005.
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