Difference Between Molecule and Ion (With Table)

The world is a beautiful place. The mountains, the sea, the sky, and all of the things that physically exist; all of these things comprise atoms. They are the universe’s building blocks. However, atoms themselves are not stable, hence, they stabilize themselves by making molecules and ions.

Molecule vs Ion

The difference between Molecule and Ion is that a molecule does not have a net charge, while an ion does. This happens because everything in this universe wants to achieve equilibrium. Atoms do this by forming molecules and ions. Also, molecules are formed by sharing electrons, whereas ions are formed due to the exchange of electrons.

One or more atoms form covalent bonds to become a molecule. The smallest unit of which a substance is made is a molecule. A molecule retains all the chemical properties of the substance. Molecules are depicted by atoms, represented using circles, forming bonds together.

A chemical species with a net positive or negative charge is known as an ion. An atom, as well as, a molecule can be termed as an ion if they non-zero net charges. Hence, all ions either have more electrons than protons or more protons than electrons in their molecular or atomic structure.

Comparison Table Between Molecule and Ion

Parameters of ComparisonMoleculeIon
Electron distributionMolecules are formed due to sharing of electrons between two or more atoms or by two oppositely charged ions.Ions are formed when atoms gain or lose charge to achieve a noble gas configuration.
SizeMolecule size depends on the size of the atoms or ions involved in the bond formation.Anions are larger than parent molecules and cations are smaller than parent molecules.
StabilityMolecules are more stable than ions.Ions are less stable than molecules.
FormationMolecules are formed by covalent bonds or ionic bonds.Ions are formed by ionic bonding between two ions of opposite charge and are stronger than covalent.
Electricity conductionSince molecules have zero net charge, they are not good conductors of electricity.Ions are good conductors of electricity.

What is a Molecule?

The smallest unit of a compound which shows the chemical properties of the compound is known as a molecule. Molecules consist of two or more atoms that are covalently bonded together, i.e., they share one or more electrons.

Molecules can be homonuclear and heteronuclear, which means they comprise the same element or different elements, respectively. Molecules make up most of the earth, and almost all organic substances are made of molecules. 

When two atoms with incomplete octets share atoms with each other, a covalent bond is formed. A covalent bond transforms the different atoms into a molecule. Molecules consist of atoms grouped together either through covalent bonds or ionic bonds. 

The covalently bonded molecules are weaker than the ionic bonded molecules. This happens because ionic bonds have a very strong electrostatic force holding the ions together. Due to this, ionic molecules are more stable than covalently bonded molecules.

What is an Ion?

An ion is a chemical species that holds a net positive or negative charge of some magnitude. Ions refer to molecules and atoms that have a non-zero net charge. Hence, ions have either more protons than electrons or more electrons than protons in their molecular or atomic structure. 

Ions that have a greater number of electrons than protons and hold a net negative charge are known as anions. Whereas, ions that have a greater number of protons than electrons and hold a net positive charge are known as cations. 

Ionic bonds are formed only when electrostatic forces arise between a negatively charged anion and a positively charged cation. These electrostatic forces attract the anions and cations to each other to stabilize the net charge. These electrostatic forces help in the formation of ionic compounds.

Ions made of only one element are referred to as atomic ions or monatomic ions. The participating atoms hold some net charge, either positive or negative. Whereas if two or more elements are involved in an ion, then they are referred to as molecular ions or polyatomic ions.

Main Differences Between Molecules and Ions

  1. Molecules do not have a net charge, whereas ions have a net positive or negative charge.
  2. Molecules are formed when two or more atoms share electrons to complete their octet, while ions exchange electrons and form ionic compounds due to electrostatic forces.
  3. Since ions are held together by electrostatic forces, they are much more stable than molecules formed by covalent bonds. 
  4. Due to high attractive forces between two ions, they have more lattice energy than the covalently bonded molecules.
  5. Because of higher lattice energy, ions are more stable than covalently bonded.
  6. The size of molecules depends on the atoms involved in the bond formations. Cations are smaller than their parent molecules, whereas anions are larger than their parent molecules.

Conclusion

Everything around us is made of atoms. Atoms by themselves are not stable. Therefore, the atoms, except inert gases, form bonds to achieve equilibrium and bring their energy down. These bonds are formed either by sharing electrons or due to strong electrostatic forces between opposite charges.

When two or more atoms share electrons and form covalent bonds, they make up molecules. Molecules do not have a net positive or negative charge. Ions, on the other hand, have net negative or positive charges.

Due to the difference in charges between two ions, electrostatic forces start to operate. Two ions of opposite charge attract each other to form ionic molecules. These molecules are more stable than covalently bonded molecules. Some examples of molecules are H2, O2, H2O, CH4, CH2O, N2, NaCl, CH3COOH etc. Some examples of ions are Al+3, Ba+2, Bi+2, Na+, Cl-, N-3, O-2, etc.

References

  1. https://ui.adsabs.harvard.edu/abs/1988STIA…8915174M/abstract
  2. https://pubs.acs.org/doi/pdf/10.1021/ja00260a006

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