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  1. Chemical reaction | Definition, Equations, Examples, & Types

    Oct 10, 2025 · A chemical reaction is a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either …

  2. Chemistry | Definition, Topics, Types, History, & Facts | Britannica

    Nov 8, 2025 · The identification of pure substances and the analysis of chemical mixtures enable all other chemical disciplines to flourish. The importance of analytical chemistry has never …

  3. Chemical compound | Definition, Examples, & Types | Britannica

    Nov 11, 2025 · All the matter in the universe is composed of the atoms of more than 100 different chemical elements, which are found both in pure form and combined in chemical compounds.

  4. Chemical element | Definition, Origins, Distribution, & Facts

    Oct 17, 2025 · A chemical element is any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which …

  5. Chemical formula | Definition, Types, Examples, & Facts | Britannica

    Nov 1, 2025 · Chemical formula, any of several kinds of expressions of the composition or structure of chemical compounds. The forms commonly encountered are empirical, molecular, …

  6. Chemical industry | Overview, Importance, & History | Britannica

    Chemical industry, complex of processes, operations, and organizations engaged in the manufacture of chemicals and their derivatives. Raw materials include fossil fuels and …

  7. Chemical Weapons Convention (CWC) | Britannica

    Chemical Weapons Convention (CWC), international treaty that bans the use of chemical weapons in war and prohibits all development, production, acquisition, stockpiling, or transfer …

  8. Chemical weapon | Convention, Definition, List, World War I, …

    Chemical weapon, any of several chemical compounds, usually toxic agents, that are intended to kill, injure, or incapacitate. In modern warfare, chemical weapons were first used in World War …

  9. DDT | Description, History, Effects, Uses, Banned, & Facts | Britannica

    Nov 7, 2025 · The chemical was widely used, though many species of insects rapidly developed resistant populations. As a result of repeated sprayings, DDT accumulated in soils in …

  10. Chemical bonding | Definition, Types, & Examples | Britannica

    Oct 30, 2025 · This article begins by describing the historical evolution of the current understanding of chemical bonding and then discusses how modern theories of the formation …