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

    Sep 26, 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.

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

    Oct 10, 2025 · Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

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

    6 days ago · Cooking, fermentation, glass making, and metallurgy are all chemical processes that date from the beginnings of civilization. Today, vinyl, Teflon, liquid crystals, semiconductors, …

  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 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 …

  6. 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 …

  7. 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, …

  8. Chemical weapon - Nerve Agents, Toxins, Warfare | Britannica

    Sep 12, 2025 · Chemical weapon - Nerve Agents, Toxins, Warfare: The most lethal and important chemical weapons contain nerve agents, which affect the transmission of impulses through the …

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

    Sep 12, 2025 · In modern warfare, chemical weapons were first used in World War I (1914–18). Like nuclear and biological weapons, chemical weapons are often classified as weapons of …

  10. Bismuth | Properties, Uses, Symbol, & Facts | Britannica

    Oct 19, 2025 · The principal chemical application of bismuth is in the form of bismuth phosphomolybdate (BiPMo 12 O 40), which is an effective catalyst for the air oxidation of …