May 12, 2025 · Chemical reactions differ from physical changes, which include changes of state, such as ice melting to water and water evaporating to vapor. If a physical change occurs, the …

Jun 19, 2025 · 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 …

Jun 22, 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 …

May 10, 2015 · A chemical element is any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which …

Although the chemical industry may be described simply as the industry that uses chemistry and manufactures chemicals, this definition is not altogether satisfactory because it leaves open …

Chemical weapon, any of several chemical compounds, usually toxic agents, that are intended to kill, injure, or incapacitate. In modern warfare, chemical weapons were first used in World War …

A chemical reaction is, by definition, one in which chemical substances are transformed into other substances, which means that chemical bonds are broken and formed so that there are …

This article begins by describing the historical evolution of the current understanding of chemical bonding and then discusses how modern theories of the formation of chemical bonds have …

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 …

Chemical engineering, the development of processes and the design and operation of plants in which materials undergo changes in their physical or chemical state. Applied throughout the …