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 …

Apr 24, 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 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 …

Apr 29, 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 …

: a substance (such as an element or compound) that is made by a chemical process

Jan 25, 2010 · Between February and September 1988 he perpetrated the Anfāl (Arabic: “Spoils”) chemical attacks on Iraqi Kurds as a reprisal for Kurdish resistance, and in March he …

The substances in a chemical reaction may be chemical elements, molecules, or compounds. The substances present at the start of a chemical reaction are called the reactants; the substances …

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 …

Apr 24, 2025 · 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 …

Chemical synthesis, the construction of complex chemical compounds from simpler ones. It is the process by which many substances important to daily life are obtained. It is applied to all types …