molecuul

A molecuul is the smallest unit of a chemical compound that retains the properties of that compound. A molecuul is made of two or more atoms held together by chemical bonds, usually covalent bonds. Molecules can be simple, such as H2O or O2, or complex, such as glucose or proteins. Some substances form discrete molecules, while many salts exist as ionic lattices rather than individual molecules in the solid state; nevertheless, molecules and ions can exist as distinct species in solution or gas phase, and polyatomic ions (for example SO4^2−) are often treated as molecular units.

The arrangement of atoms in a molecuul determines its geometry and properties. Examples include CO2, which is linear; H2O, which is bent; and CH4, which is tetrahedral. Bond angles and lengths define shape, and stereochemistry adds another layer of variation, affecting reactivity and function. Molecules can be polar or nonpolar depending on the distribution of electric charge.

Most molecules range from about 0.1 to 1 nanometer across. Their physical and chemical properties depend on composition, bond strength, polarity, and intermolecular forces such as hydrogen bonding and van der Waals interactions. Molecules are the building blocks of chemistry and biology; macromolecules like proteins and nucleic acids are large molecules formed by polymers of smaller units.

Molecules are studied using methods such as spectroscopy, X-ray crystallography, electron microscopy, and computational modeling to determine structure, dynamics, and properties.