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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. 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. How Does Metal Rust? | Science, Process, & Facts | Britannica

    Rust is the result of a chemical reaction between metal, typically iron, and oxygen in the presence of moisture. This process, known as oxidation, transforms the metal into a new compound, …

  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. Bisphenol A (BPA) | Description, Biological Effects,

    Oct 17, 2025 · Much speculation centres around whether BPA is a true endocrine disruptor chemical (EDC) in humans (broadly defined, an EDC is an exogenous substance, one that …

  6. Oxalic acid | Formula, Uses, & Facts | Britannica

    Nov 4, 2025 · The chief chemical characteristic of the carboxylic acids is their acidity. They are generally more acidic than other organic compounds containing hydroxyl groups but are …

  7. Phosgene | Toxic Gas, Chloroformyl, Industrial Uses | Britannica

    Phosgene, a colourless, chemically reactive, highly toxic gas having an odour like that of musty hay, used in making organic chemicals, dyestuffs, polycarbonate resins, and isocyanates for …

  8. Chemical Products Portal | Britannica

    Although nature provides us with a staggering amount of natural resources, humankind has also made use of a great variety of man-made compounds and substances. The chemical industry …

  9. Chemical Definition & Meaning | Britannica Dictionary

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

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

    Nov 1, 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.