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General Chemistry

Molecule

Definition and meaning of Molecule in chemistry.

A molecule is an electrically neutral group of two or more atoms held tightly together by chemical bonds. It is the smallest fundamental unit of a chemical compound that can independently take part in a chemical reaction while retaining its chemical properties.

In more detail

Molecules can consist of atoms of the identical chemical element, as seen with oxygen gas (O2), or of completely different elements, as seen with water (H2O). The atoms in a molecule share electrons through strong covalent bonds, which keeps them securely joined together in a specific geometric arrangement. Ions, which carry a net electrical charge due to the loss or gain of electrons, are not strictly classified as molecules, although the term is sometimes used loosely in biochemistry for large, complex charged structures like proteins.

Key facts

FieldGeneral Chemistry
Bond TypeCovalent bonds
Overall ChargeElectrically neutral
Example

A single molecule of carbon dioxide (CO2) contains one central carbon atom covalently bonded to two surrounding oxygen atoms.

Frequently asked questions

Is table salt (NaCl) correctly considered to be a molecule?

No, table salt is an ionic compound composed of a continuous crystalline lattice of Na+ and Cl- ions, not discrete independent molecules.

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