Difference WikiChemistry

Difference Between Molecule and Compound

Main Difference

The main difference between Molecule and Compound is that Molecule formed when similar atoms join together, whereas Compound formed when different atoms combine.

Molecule vs. Compound

The molecule is made up of two or more atoms from the same element. The compound consists of two or more atoms from different elements. In a molecule, atoms are held together with the help of a molecular bond. In the compound, there are different types of bonding atoms that can share their electrons simply or electrons completely donate to another atom by forming an ionic bond. Molecules can’t see through naked eyes. However, a compound can easily see through naked eyes.


Molecules show similar physical and chemical properties of atoms. Compounds show different chemical and physical properties of atoms after bonding. Molecules contain a limited number of atoms, whereas the compound contains an unlimited number of atoms or molecules. The smallest unit of a molecule is an atom, while the smallest component of the compound is a molecule. In molecules, electrons of the atoms are share by forming a molecular bond. In compounds, electrons are completely transferred or given to the other by making different bonds e.g., ionic, metallic, co-ordinate covalent bond, etc.

Molecules show the same shape and the same physical or chemical properties. The compound shows different physical as well as various chemical properties as compared to their elements. We can separate molecules during the chemical reaction, and we can also join them to form a large molecule. Once a compound is formed, it is not easy to separate the molecules of the compounds during the chemical reaction.


Comparison Chart

A molecule is the cluster of similar atoms, with the help of molecular bonds.A compound is the cluster of molecules or different atoms by different types of bonding.
Molecules don’t have a proper structureCompounds have a definite shape
Molecules can’t be compoundsCompounds can be molecules
Oxygen (O2), Ozone (O3), Hydrogen (H2), etcWater (H2O), Ammonia (NH3), Sodium chloride (NaCl), etc

What is a Molecule?

A molecule is the fundamental part of a compound. A molecule contains all the chemical properties that are also possessed by the compound—a molecule formed by the joining of atoms from the same element. While explaining the structure of an atom, it is also defined as “An atom is a sub-divided smaller unit of a compound which is further sub-divided into electrons, protons, and neutrons which are sub-particles of an atom.” Electron is revolving outside the nucleus of an atom, and neutron and proton are present inside the nucleus.


Protons are those species which carry positive charges and electrons carry negative charges. However, neutrons are neutral specie and possess no charge. Every element in the nucleus possess a specific number of protons called the atomic number of the element—the atomic number denoted by Z. The mass number of an atom is calculated by the sum of both protons and neutrons, and A denotes it.

Mainly atoms are vacant, but the bulky mass of a nucleus covers the center of an atom. Nucleus possesses positively charge particles i.e., protons, and that’s why the nucleus is said to charge positively. The nature of the molecule doesn’t depend on the type bond formed to join the atoms e.g., nitrogen gas contains only one kind of element in it that is nitrogen only, and they join together by the molecular bond. The carbon molecule also contains only carbon as an element in it.

What is a Compound?

A compound is formed by joining two or more molecules from different elements by making covalent or ionic bonds between them. Different types of chemical binds are present to hold the atoms together in a compound e.g., some molecules make a bond by forming a covalent bond, some make ionic bond, some are joined together by metallic bond, and some share their electrons by making co-ordinate covalent bond. A specific kind of compound can be changed into a different composition by chemical reaction with another type of compound.

Compounds are classified into two different types of compounds. One is a molecular compound, and the other is salt. In molecular compounds, atoms are joining together by making a covalent bond. However, in salts, atoms are attached by forming an ionic bond. From different molecules, to form a compound, a chemical reaction occurs to change the properties of molecules into new stabilize different properties, different colors, and different shape elements. All compounds possess a unique spatial arrangement of molecules—compounds represented by the chemical formula i.e., the information about the joining atoms.

For example, the molecule of water is represented by its chemical formula H2O. It means that a water molecule is a combination of one oxygen atom and two hydrogen atoms. In comparison molecule of hydrogen peroxide represented as H2O2, which means that it contains two hydrogen and two oxygen atoms. The like-wise chemical formula of common salt is NaCl. It shows that table salt made up of one sodium and one chlorine molecule.

Key Differences

  1. In molecules, atoms shared their electrons by simple sharing method, whereas compound shares their electrons by the partial sharing method.
  2. Molecules are small in size and light in weight; on the other hand, compounds are larger than molecules.
  3. Atoms are the essential component of molecules; conversely, molecules are essential components of a compound.
  4. A molecule contains a minimum number of atoms; on the flip side, a compound contains a maximum number of atoms.
  5. The basic component of a molecule is an atom, while the basic component of a compound is a molecule.
  6. Molecules can exist in its proper shape as compared to the compound because in compound molecules, can’t remain in their shape.
  7. The molecule is the smallest specie comparatively to a compound, and a compound is larger specie.
  8. Molecules represented by their symbols; on the other side, compounds are represented by their proper chemical formula.
  9. A molecule is a form of identical atoms. However, compounds made up of non-identical atoms.


It concluded that a molecule involves only one element in it, and the compound involves two or more types of elements.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss