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 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 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 …

Dec 9, 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 of chemical bonds have …

Jan 8, 2026 · Caffeine, nitrogenous organic compound of the alkaloid group, substances that have marked physiological effects. Caffeine occurs in tea, coffee, guarana, maté, kola nuts, and cacao. …

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

Jan 21, 2026 · Sodium bicarbonate, white crystalline or powdery solid that is a source of carbon dioxide and so is used as an ingredient in baking powders, in effervescent salts and beverages, and as a …

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 …

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 …