Chemical Bond
INTRODUCTION TO CHEMICAL BONDS
CHEMICAL BOND
Definition: A chemical bond is defined as a force that acts between two or more atoms to hold them together as a stable molecule.
Main types of bond: 1. Ionic or electrovalent bond, 2. Covalent bond, 3. Coordinate covalent bond
Forth type of bond: Metallic bond: The type of bonding which holds the atoms together in metal crystal.
Valence electron: The electrons in the outer most energy level in an atom that takes part in chemical bonding are called valence electrons.
Bonding electrons: The valence electrons actually involved in bond formation are called bonding electrons.
Octet rule: In chemical bond formation, atoms interact- (i) by losing, (ii) by gaining or (iii) by sharing electrons to acquire a stable noble gas configuration. He (2) 2 Ne (10) 2, 8 Ar (18) 2, 8, 8 Kr (36) 2, 8, 18, 8 Xe (54) 2, 8, 18, 18, 8 Rn (86) 2, 8, 18, 32, 18, 8
The tendency for atoms to have eight electrons in the outer shell is known as Octet rule.
IONIC BOND
Definition: The electrostatic attraction between the cation (+ve ions) and anions (-ve ions) produced by electron transfer constitutes an ionic or electrovalent bond.
Conditions for formation of ionic bond: 1) Bond formations occur between the metal and nonmetal. Metal is donor and nonmetal is acceptor. 2) Net lowering of energy: To form a stable ionic compound, there must be a net lowering of the energy. For example- formation of NaCl molecule (a) Na ― e → Na+ ―119 kcal (b) Cl + e → Cl‾ +85 kcal (c) Na+ + Cl‾→ Na+ Cl‾ +187 kcal Net energy released, 187 + 85 ― 119 = 153 kcal This causes lowering of energy of the process, hence ionic bond formed.
3) Electro negativity difference between the atoms Na → 0.9
CHEMICAL BOND
Definition: A chemical bond is defined as a force that acts between two or more atoms to hold them together as a stable molecule.
Main types of bond: 1. Ionic or electrovalent bond, 2. Covalent bond, 3. Coordinate covalent bond
Forth type of bond: Metallic bond: The type of bonding which holds the atoms together in metal crystal.
Valence electron: The electrons in the outer most energy level in an atom that takes part in chemical bonding are called valence electrons.
Bonding electrons: The valence electrons actually involved in bond formation are called bonding electrons.
Octet rule: In chemical bond formation, atoms interact- (i) by losing, (ii) by gaining or (iii) by sharing electrons to acquire a stable noble gas configuration. He (2) 2 Ne (10) 2, 8 Ar (18) 2, 8, 8 Kr (36) 2, 8, 18, 8 Xe (54) 2, 8, 18, 18, 8 Rn (86) 2, 8, 18, 32, 18, 8
The tendency for atoms to have eight electrons in the outer shell is known as Octet rule.
IONIC BOND
Definition: The electrostatic attraction between the cation (+ve ions) and anions (-ve ions) produced by electron transfer constitutes an ionic or electrovalent bond.
Conditions for formation of ionic bond: 1) Bond formations occur between the metal and nonmetal. Metal is donor and nonmetal is acceptor. 2) Net lowering of energy: To form a stable ionic compound, there must be a net lowering of the energy. For example- formation of NaCl molecule (a) Na ― e → Na+ ―119 kcal (b) Cl + e → Cl‾ +85 kcal (c) Na+ + Cl‾→ Na+ Cl‾ +187 kcal Net energy released, 187 + 85 ― 119 = 153 kcal This causes lowering of energy of the process, hence ionic bond formed.
3) Electro negativity difference between the atoms Na → 0.9