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 13, 2026 · Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

CHEMICAL meaning: 1 : of or relating to chemistry; 2 : working by means of chemicals

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 …

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 …

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

Dec 10, 2025 · Chlorine, chemical element of the halogen group that is a toxic, corrosive, greenish yellow gas, irritating to the eyes and respiratory system. Much chlorine is used to sterilize water and …

Jan 16, 2026 · Photosynthesis is the process by which green plants and certain other organisms transform light energy into chemical energy. During photosynthesis in green plants, light energy is …