molécule

A molecule is a group of two or more atoms held together by chemical bonds. These atoms can be of the same element, such as in an oxygen molecule (O2), which consists of two oxygen atoms. Alternatively, the atoms can be of different elements, forming a compound. Water (H2O), for example, is a molecule composed of two hydrogen atoms and one oxygen atom. The atoms within a molecule are arranged in a specific, fixed spatial relationship, defining the molecule's unique structure.

The properties of a molecule are determined by the types of atoms it contains, the number of each atom, and how they are bonded together. These properties can range from physical characteristics like boiling point and melting point to chemical reactivity. Molecules are the fundamental building blocks of most substances we encounter in everyday life, from air and water to complex organic compounds like DNA. They are essential for all biological processes and chemical reactions. The smallest unit of a chemical compound that can exist independently and retain all of its chemical and physical properties is a molecule.