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  1. What Is a Chemical? Definition and Examples

    Oct 15, 2023 · Chemicals come in various forms depending on their composition, structure, and how they interact with other substances. Understanding the main types of chemicals helps …

  2. Chemistry | Definition, Topics, Types, History, & Facts ...

    Dec 26, 2025 · chemistry, the science that deals with the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the …

  3. What is a Chemical ? | Nuclear Regulatory Commission - NRC

    Chemical changes are different from physical changes, which don't result in a change in substances. One example of a physical change is when water freezes into ice. While ice may …

  4. Substance (chemistry) - Wikipedia

    Chemical substances can exist in several different physical states or phases (e.g. solids, liquids, gases, or plasma) without changing their chemical composition. Substances transition …

  5. PubChem

    Search chemicals by name, molecular formula, structure, and other identifiers. Find chemical and physical properties, biological activities, safety and toxicity information, patents, literature …

  6. Chemicals, Pesticides and Toxics Topics | US EPA

    May 15, 2025 · Learn how to safely handle chemicals, the effects of certain toxins, which substances are controlled or managed, and safer alternatives.

  7. CHEMICAL Definition & Meaning - Merriam-Webster

    The meaning of CHEMICAL is of, relating to, used in, or produced by chemistry or the phenomena of chemistry. How to use chemical in a sentence.