Free Chemistry Dictionary

Video Example : Molecule



  • Chemical bond
  • Atomicity
  • Compound
  • Atoms and complexes
  • Macromolecule
  • Macroscopic sizes
  • Polymer
  • Organic synthesis

Definition of Molecule

Molecule is the smallest particle of matter that can exist individually

More About Molecule

  • A molecule is in general a group of atoms that exist together
  • A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.
  • Molecules are distinguished from ions by their lack of electrical charge
  • Atoms of different elements join together to form molecules
  • The atoms are held together tightly by attractive forces
  • Atoms of same element or different elements can join together to form molecules
  • The molecules of an element are constituted by the same type of atoms
  • Molecules of many elements are having only one atom. Eg. Helium, argon, neon
  • In most non metals, the molecule contains more than one element. One molecule of oxygen contains two atoms of oxygen
  • One molecule of ozone contains three atoms of oxygen
  • The number of atoms present in a molecule is known as its atomicity
  • A molecule is formed when two or more atoms join together chemically.
  • A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds.
  • Molecular hydrogen ( H2), molecular oxygen ( O2) and molecular nitrogen ( N2) are not compounds because each is composed of a single element
  • Water ( H2O), carbon dioxide ( CO2) and methane ( CH4) are compounds because each is made from more than one element. The smallest bit of each of these substances would be referred to as a molecule.
  • A single molecule of molecular hydrogen is made from two atoms of hydrogen while a single molecule of water is made from two atoms of hydrogen and one atom of oxygen.
  • Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules.
  • Molecules as components of matter are common in organic substances. They also make up most of the oceans and atmosphere
  • Most molecules are far too small to be seen with the naked eye, but there are exceptions
  • DNA, a macromolecule, can reach macroscopic sizes, as can molecules of many polymers
  • Molecules commonly used as building blocks for organic synthesis have a dimension of a few angstroms (Ao ) to several dozen Ao
  • Some of the largest molecules are macromolecules or super molecules