Sep 26, 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.

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 …

Sep 23, 2025 · The identification of pure substances and the analysis of chemical mixtures enable all other chemical disciplines to flourish. The importance of analytical chemistry has never …

Sep 20, 2025 · Chemical formula, any of several kinds of expressions of the composition or structure of chemical compounds. The forms commonly encountered are empirical, molecular, …

Sep 12, 2025 · 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 …

Chemical industry, complex of processes, operations, and organizations engaged in the manufacture of chemicals and their derivatives. Raw materials include fossil fuels and …

Oct 10, 2025 · Chemical reaction - Energy, Reactants, Products: Energy plays a key role in chemical processes. According to the modern view of chemical reactions, bonds between …

Sep 5, 2025 · This article begins by describing the historical evolution of the current understanding of chemical bonding and then discusses how modern theories of the formation …

Sep 15, 2025 · Krypton (Kr), chemical element, a rare gas of Group 18 (noble gases) of the periodic table, which forms relatively few chemical compounds. About three times heavier than …

Sep 12, 2025 · Chemical weapon - Banning, Prohibition, Conventions: During World War I, Germany, France, the United Kingdom, and Russia developed a wide array of chemical arms, …