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

    Apr 24, 2025 · Most of the materials that occur on Earth, such as wood, coal, minerals, or air, are mixtures of many different and distinct chemical substances. Each pure chemical substance …

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

    May 12, 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 …

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

    Chemical compound, any substance composed of identical molecules consisting of atoms of two or more chemical elements. All the matter in the universe is composed of the atoms of more …

  4. Chemical Definition & Meaning | Britannica Dictionary

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

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

    Apr 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 …

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

    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 reaction - Students | Britannica Kids | Homework Help

    To describe chemical reactions, scientists use chemical equations, which make use of symbols and formulas for elements and compounds. The chemical equation for the reaction between …

  8. list of chemical elements - Encyclopedia Britannica

    May 10, 2015 · A chemical element is any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which …

  9. chemical energy - Kids | Britannica Kids | Homework Help

    Chemical energy is a form of potential energy that is in all substances. Food is the most important source of chemical energy for living things. The chemical energy in food is converted, or …

  10. Chemical engineering | Processes, Principles & Applications

    Chemical engineering, the development of processes and the design and operation of plants in which materials undergo changes in their physical or chemical state. Applied throughout the …