Matter can be classified as either pure substances or mixtures. Pure substances have a fixed composition and include elements, which contain only one type of atom, and compounds, which contain two or more elements in a fixed ratio. Mixtures have a variable composition and include homogeneous mixtures, which are uniform throughout, and heterogeneous mixtures, where the distinct components can be seen. The document provides examples of elements, compounds, and mixtures to illustrate these classifications.
3. Classification of Matter Pure Substances Fixed Composition Mixtures Variable Composition Howdoyouturnthison. A plate of dolly mixture. 29 July 2008. http://commons.wikimedia.org/wiki/File:Dolly_mixture.JPG
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5. All discovered elements are listed in a periodic tableAccordion Guy. Periodic Table of Google Images. September 2006. http://www.neatorama.com/2006/09/24/
There are two kinds of pure substances: elements and compoundsElements are made up of only one type of atom. Examples are copper, aluminum, and hydrogen. All the elements discovered thus far are shown in a periodic table.
Compounds are made of two or more elements or atoms. Examples are water, hydrogen peroxide and table sugar. The ratio of the elements in a given compound is fixed. For example, the ratio of hydrogen to oxygen in water is 2 atoms of hydrogen to 1 atom of oxygen. In hydrogen peroxide, hydrogen and oxygen are also combined, but the ratio is 2 atoms of hydrogen to 2 atoms of oxygen. Water and hydrogen peroxide are different compounds with different properties.
