Chemical Bonding and Compound
Chemical bond meaning the different types of force bonding together two common atoms or groups of atoms forming an aggregate of ions or molecular species such that there occurs lowering of energy. The definition of chemical bonds or bonding explain the different types of properties of the ionic bond, covalent bond, metallic bonded metal, and non-metal compound in chemistry. But there will be many examples of bonding compounds whose properties and structure indicate the bonds of intermediate types, which are called the coordinate covalent bond. The fundamental questions for study chemistry, since the beginning, the forces responsible for the formation of bonds in the chemical compound.
After nearly a century of confusion, Kekul, Van’t Hoff, Le Bel, Lewis, and London, etc in the nineteenth century given the definition 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 compound has a saturation capacity for the formation of the bond. The valency commonly used for the saturation capacity of an element for forming the bonding.
Different Types of Chemical Bonding
Ionic, covalent, and metallic bonding in metal meaning different types of forces that bonded the atom or ion in a chemical compound. But in coordinate covalent chemical bonding, properties and bonded structure indicate the bond with intermediate types.
Meaning and Definition of Ionic Bond
The electrostatic forces bind together oppositely charged ions in chemical compounds responsible for the formation of ionic bonds. Thus ionic bonding structure 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 and electronegative elements have a tendency to gain these electrons. As a result of mutual electrostatic attraction between positive and negative ion establishes the ionic or electrostatic bond
Examples of Ionic Bonds
NaCl, KCl, MgCl3, CaCl2, etc are the examples for the formation of crystalline compounds with ionic bonds. Crystallographic studies of sodium chloride show, there is no discrete sodium chloride. Hence in sodium chloride crystal lattice, 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 ionization. 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
Definition of Covalent Chemical Bonding
A covalent bond meaning the 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 meaning of the covalent bond between two hydrogens or two chlorine atoms easily understands. 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 bonded 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.
Hydrogen ⇒ 1S1
Fluorine ⇒ 1S2 2S2 2P5
H• + •F → H• •F or H-F
Therefore, hydrogen attains helium, and fluorine attains neon electron configuration.
Examples of Coordinate Covalent Bonds
But the sharing of electrons equal to the partner not common for the definition of covalent chemical bonds sometimes. For the formation of the bond between BF3 and NH3, both the electrons come from NH3.
Hence such type of bonding is an example of a coordinate covalent bond. So here NH3 as a donner and BF3 is an acceptor. Here NH3 behaves like a lewis base and BF3 as a lewis acid.
NH3 + BF3 → F3B←:NH3
Chemical Bonding in Metallic Compound
Metals are a good conductor of electricity and thermal energy. Therefore the formation of the metallic bonds given crystalline solid with high coordination numbers of 12 or 14. When the atoms in a metal are identical they can not show ionic properties. Therefore 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, the metallic crystal may be a collection of positive atomic cores in a fluid of mobile electrons in the electron sea model. In this electron sea model, the force that binds a metal ion to the mobile electrons responsible for the formation of the metallic bond.
Common Properties of Metallic Bond in Metal
The electron sea model in the metallic bond easily explains the properties of conductivity and heat conduction in the metal bonded 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 by the electron sea model definition.
Therefore, from the definition and structure of the ionic bond, covalent or coordinate covalent bonding, and metallic bonds in the metal can explain most of the common types of properties of the chemical compound. Another type of bonding, meaning Hydrogen bond uses for explaining the common physical properties of compound or molecule in chemistry.