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.

Nov 30, 2025 · Substances are either chemical elements or compounds. A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products.

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 …

Nov 1, 2025 · Chemical formula, any of several kinds of expressions of the composition or structure of chemical compounds. The forms commonly encountered are empirical, molecular, structural, and …

Nov 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 all …

Chemical symbol, short notation derived from the scientific name of a chemical element—e.g., S for sulfur and Si for silicon. Sometimes the symbol is derived from the Latin name—e.g., Au for aurum, …

Dec 4, 2025 · A chemical reaction rearranges the constituent atoms of the reactants to create different substances as products. Chemical reactions are an integral part of technology, of culture, and indeed …

Compounds can be broken down into their constituents to various degrees or changed into new compounds by chemical reactions. Atoms always combine into molecules in fixed proportions, …

Nov 27, 2025 · Metabolism, the sum of chemical reactions that take place in living cells, providing energy for life processes and the synthesis of cellular material. Living organisms are unique in that …

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 …