CBSE Class 11-science Chemistry Chemical Bonding and Molecular Structure
Chemical Bonding
A force which binds atoms of same or different elements by mutual sharing of electrons is called a covalent bond.
The Lewis dot structures show the arrangement of bonded pairs and lone pairs around
The octet rule is a simple chemical rule of thumb that states that atoms tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas.Ionic Bond
As per octet rule each atom wants to share, lose or gain electrons until it has eight electrons in the valence shell.
Ionic bond is electrostatic force of attraction between two oppositely charged atoms or group of atoms.
Covalent bond is formed by sharing of valence electrons.Bond Parameters
Bond length is equilibrium distance between two bonded atoms. Bond angle is the angle between orbital containing bond pair of electron.
Bond enthalpy is the energy required to break one mole of bond and is significant in determining the property of molecules.
Enthalpy of reaction is calculated from bond enthalpies of the reactants and the products.Hybridization
Valence bond theory describes the covalent bond in terms of overlap of atomic orbitals.
Hybrid orbitals result from the mixing of atomic orbitals on the same atom.
The orbitals undergoing hybridisation should have only a small difference in energy and they should be present in the valence shell of the atom.Geometry and Shapes of Molecules
According to VSEPR theory, each molecule adopts a geometry or shape that allows for minimum repulsions between electron pairs by simply maximising the distance between them
VSEPR Theory predicts the shapes of molecules based on least possible energy.Resonance and Hydrogen Bond
Hydrogen bond is the attractive force binding hydrogen atom of one molecule with the electronegative atom like f, o or n of another molecule and influences the state and physical properties of the compounds.
Pair of electrons in the multiple bonds are delocalised and structures so formed are called resonating or canonical structures.Molecular Orbital Theory
Atomic orbitals combine to form molecular orbitals, bonding and anti-bonding (a-b).
Bonding molecular orbitals are at lower energy than the atomic orbitals and anti-bonding molecular orbitals with higher energy than the atomic orbital.
The stability and magnetic character of the molecule depends on the number of electrons in the bonding and anti-bonding.
