Ionic Bonding vs Metallic Bonding
As proposed by the American chemist G.N.Lewis, 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 the 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 can be done by forming ionic bonds, covalent bonds or metallic bonds.
Atoms can gain or lose electrons and form negative or positive charged particles respectively. These particles are called ions. There are electrostatic interactions between the ions. Ionic bonding is the attractive force between these oppositely charged ions. The strength of the electrostatic interactions is largely influenced by the electronegativities of the atoms in an ionic bond. 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. 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.
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 called metallic bonding. Metals release electrons in their outer shells, and these electrons are dispersed between metal cations. Therefore, they are known as a sea of delocalized electrons. The electrostatic interactions between the electrons and cations are called metallic bonding. The number of electrons released 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 the number of electrons released is directly proportional to the metallic bond strength. The electrons can move, therefore 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 strength of metallic bonding.
What’s the difference between Ionic Bonding and Metallic Bonding?
– Ionic bonding takes place between positive and negative ions. Metallic bonding takes place between positive ions and electrons.
– Since same type of atoms is participating in metallic bonding, there is no electron negativity difference between two atoms like in ionic bonding.
– Ionic bonds are much stronger than metallic bonds.
– Ionic compounds do not conduct electricity, unless they are in the molten form or dissolved in a solution. But metals can conduct electricity in the solid state.