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The bond formed by atoms by mutually sharing their electron pairs is known as covalent bond. Compounds with covalent bonds are poor conductor of electricity. The covalently bonded molecules have strong bond within the molecules,but their inter-molecular forces are weak. This makes the boiling and melting point of these compounds low.
When electron breaks a covalent bond then at the place of electron a hole is created and thus due to this vacant place occupied by holes a valency is created in broken covalent bond.
• Ionic bonding is the complete transfer of valence electron between atoms.
• It is a type of chemical bond that generates two oppositely charged ions.
• It results from gaining, losing & transfer of electrons
• Covalent bonding occurs when pairs of electrons are shared by atoms.
In HF molecule, the hydrogen bond exists between the hydrogen atom of one molecule and a fluorine atom of another molecule as depicted below;
----Hδ + - Fδ - -----Hδ + - Fδ - -----Hδ + - Fδ –
Here, hydrogen bond acts as a bridge between two atoms which holds one atom by a covalent bond and the other by a hydrogen bond.
Hydrogen-bond is represented by a dotted line (----) while a solid line represents the covalent bond.
Thus, Option B is the correct answer.
Merging (mixing) of dissimilar orbitals of different energies to form new orbitals is known as hybridisation and the new orbital formed are known as hybrid oribitals. They have similar energy.
The bond angle in alcohols is slightly less than the tetrahedral angle (109-28’). It is due to the repulsion between the unshared electron pairs of oxygen.
Thus, Option A is the correct answer.
Bond Angle: It is defined as the angle between the orbitals containing bonding electron pairs around central atom in a molecule / complex ion.
Thus, Option C is the correct answer.
Covalent compounds have weak forces of attraction between the binding molecules. Thus less energy is required to break the force of bonding. Therefore, covalent compounds have low melting and boiling point.
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