Feb 3, 2026 · Chemistry is the science of the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is …

Feb 10, 2026 · 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.

Jan 19, 2026 · A mole is defined as 6.02214076 × 10 23 of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, …

According to the modern view of chemical reactions, bonds between atoms in the reactants must be broken, and the atoms or pieces of molecules are reassembled into products by forming new bonds. …

Jan 9, 2026 · 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 …

Jan 13, 2026 · 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 …

Feb 7, 2026 · Salt, in chemistry, substance produced by the reaction of an acid with a base. A salt consists of the positive ion (cation) of a base and the negative ion (anion) of an acid.

Jan 21, 2026 · Metal, any of a class of substances characterized by high electrical and thermal conductivity as well as by malleability, ductility, and high reflectivity of light. Approximately three …

Dec 12, 2025 · What is an acid, as defined in chemistry? An acid is any substance that in water solution tastes sour, changes blue litmus paper to red, reacts with some metals to liberate hydrogen, reacts …

Jan 27, 2026 · An oxidation-reduction reaction is any chemical reaction in which the oxidation number of a participating chemical species changes. Many such reactions are common and …