element

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element, in chemistry, a substance that cannot be decomposed into simpler substances by chemical means. A substance such as a compound can be decomposed into its constituent elements by means of a chemical reaction, but no further simplification can be achieved. An element can, however, be decomposed into simpler substances, such as protons and neutrons or various combinations of them, by the methods of particle physics, e.g., by bombardment of the nucleus.

Sections in this article:

• Introduction
• Discovery of the Elements
• Evolution of Modern Concepts
• Greek Concept of the Elements
• The Elements through the Ages
• Official Symbols and Names for the Elements
• Properties of the Elements
• Atomic Mass and Atomic Weight
• Isotopes
• Atomic Number and Mass Number
• The Atom
• Bibliography

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2025, Columbia University Press. All rights reserved.

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