The key difference between ionic bonding and metallic bonding is that the ionic bonding takes place between positive and negative ions whereas the metallic bonding takes place between positive ions and electrons.
As American chemist G.N.Lewis proposed, atoms are stable when they contain eight electrons in their valence shell. Most of the atoms have less than eight electrons in their valence shells (except the noble gases in group 18 of the periodic table); therefore, they are not stable. These atoms tend to react with each other to become stable. Thus, each atom can achieve a noble gas electronic configuration. This occurs by forming ionic bonds, covalent bonds or metallic bonds.
CONTENTS
1. Overview and Key Difference
2. What is Ionic Bonding
3. What is Metallic Bonding
4. Side by Side Comparison – Ionic Bonding vs Metallic Bonding in Tabular Form
5. Summary
What is Ionic Bonding?
Atoms can gain or lose electrons and form negative or positive charged particles respectively. These particles are “ions”. There are electrostatic interactions between these ions. Accordingly, ionic bonding is the attraction force between these oppositely charged ions.
The electronegativity of the atoms in an ionic bond influences the strength of the electrostatic interactions. Hence, electronegativity gives a measurement of the atoms’ affinity for electrons. An atom with high electronegativity can attract electrons from an atom with low electronegativity to form an ionic bond.
Figure 01: Ionic Bonding
For example, sodium chloride has an ionic bond between sodium ion and chloride ion. Sodium is a metal; therefore, it has a very low electronegativity (0.9) compared to Chlorine (3.0). Because of this electronegativity difference, Chlorine can attract an electron from Sodium and form Cl– and Na+ ions. Because of this, both atoms gain the stable, noble gas electronic configuration. Cl– and Na+ are held together by attractive electrostatic forces, thus forming an ionic bond.
What is Metallic Bonding?
Metals are atoms, which can form cations by removing electrons. Group 1, group 2 and transition elements are metals. Most of the time metals are in the solid phase. The type of bond forms between metal atoms is “metallic bond”.
Metals release electrons in their outer shells and these electrons disperse between metal cations. Therefore, we call it a “sea of delocalized electrons”. The electrostatic interactions between the electrons and cations are called metallic bonding.
Figure 02: Metallic Bonding
The number of electrons that the metal atoms release into the sea and the size of the cation determines the strength of the metallic bond. Size of the cations is inversely proportional to the strength of the bond, and also the number of electrons that a metal atom releases are directly proportional to the metallic bond strength.
Moreover, the electrons can move; thus, metals have the ability to conduct electricity. Because of the metallic bonding metals have an ordered structure. High melting points and boiling points of metals are also due to this strong metallic bonding. Metals are strong and not brittle, due to the same reason.
What is the Difference Between Ionic Bonding and Metallic Bonding?
Ionic bonding is a type of chemical bond that occurs between two oppositely charged ions while metallic bonding is the type of chemical bond that occurs in a metal lattice. Hence, the key difference between ionic bonding and metallic bonding is that the ionic bonding takes place between positive and negative ions whereas the metallic bonding takes place between positive ions and electrons.
As another important difference between ionic bonding and metallic bonding, we can consider the influence of the electronegativity of atoms on the bond strength. That is; the electronegativity has no influence on metallic bonding since the same type of atoms are involved in bonding but, the strength of bonding is greatly influenced by the electronegativity difference between positive and negative ions in ionic bonding. Furthermore, ionic bonding is much stronger than the metallic bonding.
The below infographic on difference between ionic bonding and metallic bonding shows more differences between both bonds.
Summary – Ionic Bonding vs Metallic Bonding
There are three major types of chemical bonding. They are the ionic bonding, covalent bonding and metallic bonding. The key difference between ionic bonding and metallic bonding is that the ionic bonding takes place between positive and negative ions whereas the metallic bonding takes place between positive ions and electrons.
Reference:
1. Libretexts. “Ionic and Covalent Bonds.” Chemistry LibreTexts, National Science Foundation, 28 Feb. 2018. Available here
2. Libretexts. “Metallic Bonding.” Chemistry LibreTexts, National Science Foundation, 31 July 2018. Available here
Image Courtesy:
1.”Ionic bonding”By EliseEtc – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.”Metallic bonding”By Muskid – Own work, (CC BY-SA 3.0) via Commons Wikimedia