Dec 16, 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.

Dec 26, 2025 · Cooking, fermentation, glass making, and metallurgy are all chemical processes that date from the beginnings of civilization. Today, vinyl, Teflon, liquid crystals, semiconductors, and …

Jan 24, 2026 · gold (Au), chemical element, a dense lustrous yellow precious metal of Group 11 (Ib), Period 6, of the periodic table of the elements. Gold has several qualities that have made it …

Jan 9, 2026 · Cellular respiration, the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and …

Jan 23, 2026 · Ethanol is an important industrial chemical; it is used as a solvent, in the synthesis of other organic chemicals, and as an additive to gasoline. It is also the intoxicating ingredient of many …

Dec 27, 2025 · Nitric oxide, colourless toxic gas that has important chemical signaling functions in animals and is a serious air pollutant.

Jan 12, 2026 · A chemical change (that is, a chemical reaction) is one in which the organization of the atoms is altered. An example of a chemical reaction is the burning of methane in the presence of …

Dec 22, 2025 · Periodic table, in chemistry, is an organized array of all the chemical elements in order of increasing atomic number. When the elements are thus arranged, there is a recurring pattern in …

Jan 8, 2026 · Mercury, chemical element, liquid metal of Group 12 of the periodic table. Mercury is the only elemental metal that is liquid at room temperature. Mercury is silvery white and slowly tarnishes …

Jan 13, 2026 · This section describes the structure and physical and chemical properties of fatty acids. It also explains how living organisms obtain fatty acids, both from their diets and through metabolic …