Ionic Covalent Metallic Bonding
The ionic, covalent, coordinate covalent, and metallic compounds are examples for the formation of different types of bonding within the common chemical compound. But the properties of ionic, covalent, coordinate, and metallic bond is different for the different types of compounds.
Therefore the forced binding together two atoms or groups of atoms forming an aggregate of ions or molecular species by lowering the energy of the electron.
Here the fundamental questions for chemical science since the beginning, the forces responsible for the formation of bonds in the chemical compounds.
After nearly a century of confusion, Kekul, Van’t Hoff, Le Bel, Lewis, and London, etc in the nineteenth century given the concept of the chemical bonding.
It was easily realized that the number of atoms or groups of atoms combines to form the ions or molecules. Thus every chemical has a saturation capacity for the formation of bond. The valency commonly used for the saturation capacity of an element for forming the bonding.
What are the Different Types of Chemical Bonding?
For study different types of force holding together on atoms or ions, the chemical compound form three common types of bonds.
- Ionic, electrovalent, electrostatic
Ionic, covalent, and metallic bonding types represent different types of forces in the chemical compounds. But there many chemical compounds whose properties indicate the bond with intermediate types.
Formation of Ionic Compounds
The electrostatic forces bind together oppositely charged ions in chemical compounds responsible for the formation of ionic bonds. It formed by the transfer of electron or electrons from an electropositive metal to an electronegative non-metal atom.
Electropositive elements have a tendency to lose one or more electrons. But electronegative elements have a tendency to gain electrons.
Examples of Ionic Bonding
NaCl, KCl, MgCl3, CaCl2, etc are the examples for the formation of crystalline compounds with ionic bonding.
Crystallographic studies of sodium chloride show, there is no discrete sodium chloride. Hence in sodium chloride crystal, each sodium ion surrounded by six chlorine atom or vice versa.
Therefore two oppositely charged ions held together by the electrostatic force of attraction. Each sodium atom loses one electron to form uni positive sodium ion. But chlorine atom gains this electron to form uni negative ion.
These two ions formed a close-packed crystalline sodium chloride compound.
Na → Na+ + e
Cl + e → Cl–
Na+ + Cl– → NaCl
Formation of Covalent Bond with Example
A covalent bond may be defined as a force holding together atoms through the sharing of electrons.
We easily understand the formation of an ionic bond in chemical compounds by electrostatic attraction between two oppositely charged ions. But much difficulty in understanding covalent bonding.
Therefore the examples of the covalent bonding between two hydrogens or two chlorine atoms easily understand. Because there is no electronegativity difference between two identical atoms.
But electron transfers more reasonable when two atoms with wide differences in electronegativity. Thus HF forms by ionic bond because the electronegativity of hydrogen and fluorine are different.
The properties of HF differ from the characteristic of the ionic compounds. HF is a nonconductor of electricity and a low boiling point.
Lewis suggested that such covalent compounds formed by the sharing of electrons between the atoms and each atom can attain a noble gas electron configuration.
|1S1||1S2 2S2 2P5|
H• + •F → H• •F or H-F
Thus hydrogen attains helium and fluorine attain neon electron configuration.
Properties of Coordinate Covalent Bond
But the sharing of electrons equal to the partner not common for the formation of covalent types chemical bonds sometimes.
For the formation of the bond between BF3 and NH3, both the electrons come from NH3. Hence such type of bond is an example of a coordinate covalent bond. So here NH3 as a donner and BF3 is an acceptor.
NH3 + BF3 → F3B←:NH3
Chemical Bonding in Metallic Compounds
When the atoms in a metal are identical they can not show ionic properties. Because the ionic compounds are formed between two different atoms.
Covalent chemical bonding also not possible for metal. In covalent compounds much weak Van der Waals force acting between the two atoms. It can not explain the rigidity of the metal atom.
Therefore metallic crystal may be a collection of positive atomic cores in a fluid of mobile electrons. In this electron sea model, the force that binds a metal ion to the mobile electrons responsible for the formation of the metallic bond.
Properties of Metallic Compounds
Metallic bond easily explains the properties of conductivity and heat conduction in the metal compounds.
- Under the influence of the electric field, the electrons of the metal move through the lattice. Thus metals are the conductor of electricity.
- Heat conduction appears due to motion in electrons. Hence the higher energy transfers some energy to mobile electrons. But these electrons move one atomic core to another. Thus metal is the conductor of heat.
Although most of the properties of the metal can explain by metallic bonds but the heat capacity of metals difficult to explain.
Therefore covalent, ionic, coordinate, and metallic bond explains most of the common physical and chemical properties in chemistry. Another type of bond-like Hydrogen bond also describes some physical properties of molecules.