Simple Substance

a homogeneous substance composed of the atoms of a chemical element; the form of a chemical element existing in a free state. The simple substances diamond, graphite, and coal, for example, are composed of atoms of the element carbon but differ in their structures and properties. Ordinary oxygen O₂ and ozone O₃ are composed of atoms of the element oxygen but have different molecular weights and very different properties.

The concepts of simple substance and chemical element are often confused even in contemporary literature because the chemical elements and the simple substances they form are usually known by one and the same name. Special names or letter designations are only assigned to those elements that exist in various modified forms, such as white, red, and black phosphorus and white and gray tin (β-Sn and α-Sn, respectively).

单词	simple substance
释义	Simple Substance Simple Substance a homogeneous substance composed of the atoms of a chemical element; the form of a chemical element existing in a free state. The simple substances diamond, graphite, and coal, for example, are composed of atoms of the element carbon but differ in their structures and properties. Ordinary oxygen O₂ and ozone O₃ are composed of atoms of the element oxygen but have different molecular weights and very different properties. The concepts of simple substance and chemical element are often confused even in contemporary literature because the chemical elements and the simple substances they form are usually known by one and the same name. Special names or letter designations are only assigned to those elements that exist in various modified forms, such as white, red, and black phosphorus and white and gray tin (β-Sn and α-Sn, respectively).
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