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

    Nov 30, 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 chemical …

  2. 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.

  3. 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 been greater …

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

    Nov 29, 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 all …

  5. Chemical Definition & Meaning | Britannica Dictionary

    CHEMICAL meaning: 1 : of or relating to chemistry; 2 : working by means of chemicals

  6. 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, structural, and …

  7. Chemical element - Atomic Structure, Periodic Table, Properties ...

    Nov 29, 2025 · Chemical element - Atomic Structure, Periodic Table, Properties: Paralleling the development of the concept of elements was an understanding of the nature of matter. At various …

  8. Chemical bonding - Ionic, Covalent, Compounds | Britannica

    Oct 30, 2025 · The difference between the two classes gave rise to the view that there are two types of chemical bond. Electrolytes produce ions in solution; an ion is an electrically charged atom and …

  9. Chemical energy | Definition & Facts | Britannica

    The chemical energy in food is converted by the body into mechanical energy and heat. The chemical energy in coal is converted into electrical energy at a power plant. The chemical energy in a battery …

  10. Chemical engineering | Processes, Principles & Applications | Britannica

    Oct 10, 2025 · The fundamental principles of chemical engineering underlie the operation of processes extending well beyond the boundaries of the chemical industry, and chemical engineers are …