2025年3月24日 · 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 elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

2025年3月26日 · 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 composed. Learn more about the origins, distribution, and characteristics of chemical elements in this article.

2025年3月20日 · 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 (e.g., oxygen, iron, or water) has a characteristic set of properties that gives it its

2025年4月3日 · 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 than 100 different chemical elements, which are found both in pure form and combined in chemical compounds.

2025年4月1日 · vanadium (V), chemical element, silvery white soft metal of Group 5 (Vb) of the periodic table. It is alloyed with steel and iron for high-speed tool steel, high-strength low-alloy steel, and wear-resistant cast iron.

2025年3月24日 · Chemical bonding, any of the interactions that account for the association of atoms into molecules, ions, crystals, and other species. When atoms approach one another, their electrons interact and tend to distribute themselves in space so that the total energy is lower than it would be in any alternative arrangement.

2025年3月24日 · Chemical reaction - Bronsted-Lowry, Acids, Bases: A somewhat more general acid-base theory, the Brønsted-Lowry theory, named after Danish chemist Johannes Nicolaus Brønsted and English chemist Thomas Martin Lowry, defines an acid as a proton donor and a base as a proton acceptor.

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 projection formulas.

2025年3月6日 · Chemical castration is the use of drugs to suppress the production of sex hormones. It differs from surgical castration in that it is reversible and its effects typically stop when the drugs are ceased.

Chemical weapon - WMD, Toxins, Agents: Chemical weapons did not become true weapons of mass destruction (WMD) until they were introduced in their modern form in World War I (1914–18). The German army initiated modern chemical warfare by launching a chlorine attack at Ypres, Belgium, on April 22, 1915, killing 5,000 French and Algerian troops ...