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

    Jun 22, 2025 · Cooking, fermentation, glass making, and metallurgy are all chemical processes that date from the beginnings of civilization. Today, vinyl, Teflon, liquid crystals, …

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

    May 12, 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. Chemical compound | Definition, Examples, & Types | Britannica

    Jun 19, 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 Definition & Meaning | Britannica Dictionary

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

  5. Photosynthesis | Definition, Formula, Process, Diagram, Reactants ...

    Jun 9, 2025 · Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light …

  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. list of chemical elements - Encyclopedia Britannica

    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 matter is …

  8. Cellular respiration | Definition, Equation, Cycle, Process, Reactants ...

    Cellular respiration, the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and discarding, …

  9. Human body | Organs, Systems, Structure, Diagram, & Facts

    Jun 22, 2025 · Chemical composition of the body Chemically, the human body consists mainly of water and of organic compounds —i.e., lipids, proteins, carbohydrates, and nucleic acids.

  10. Chemical synthesis | Organic & Inorganic Reactions | Britannica

    Chemical compounds are made up of atoms of different elements, joined together by chemical bonds. A chemical synthesis usually involves the breaking of existing bonds and the formation …