CHEMICAL BONDING
Chemical bonding is a very important part of the syllabus and
plays an important role in understanding several other chapters
in inorganic chemistry. Further, IIT has often asked questions
on this and other related chapters.
Important Points:
1. ORBITAL OVERLAP
CONDITIONS FOR RESONANCE:
1. Identical arrangement of atoms.
2. Same number of unpaired electrons.
3. Similar energy content.
4. Planar.
5. Delocalisation.
FEATURES OF HYBRIDIZATION:
1. No of hybrid orbitals=No of atomic orbitals
2. Equivalent in shape and energy.
3. More effective in forming stable bonds.
4. Directed in space in a preferred direction to reduce repulsion.
CONDITIONS FOR HYBRIDIZATION:
1. Promotion of electron is not essential.
2. Both fully filled and half filled orbitals can take place in
hybridization.
HYDROGEN BONDING- CONSEQUENCES
1. Higher boiling points of H2O , NH3, HF.
2. Increase in melting point, boiling point,solubility and viscosity
of many compounds.
3. Viscosity of Phosphoric acid and Glycerol.
4. Dimer formation in carboxylic acid and hexamer formation
in HF.
5. Negative azeotropy of mixtures of HF with water.
6. Ice is less dense than water - When water freezes, water
molecules form a crystalline structure maintained by hydrogen
bonding. The orientation of these bonds causes molecules in
ice to move apart from each other.
POLARIZATION:
1. Cation should be small and anion should be large.
2. Both should have high charge.
3. Cations with pseudo inert config have higher polarizing
power.
4. Pseudo > non inert > inert
5. Polarization is proportional to acidic character.
6. Polarization is proportional to color intensity.
VSEPR THEORY:
MOLECULAR ORBITAL THEORY
MISCELLANEOUS POINTS:
1. More electronegative element prefers to stay at axial
position whereas lone pair prefers to stay at equatorial
position( only for TBP).
2. % of p character is proportional to length and thinness of
bonds.% of s character is proportional to repulsion.
3. The more electronegative element prefers to stay in the
orbital having more p character and it also increases p
character in the attached orbital.
eg. In CH2F2 the C-F bond has more p character and is
longer than C-H bond. Hence C-H bonds repel each other
more and H-C-H bond angle is greater than F-C-F.
4. Back bonding: In molecules like NCl3 and Cl2O, the bond
angle is greater than expected. This is due to back bonding
which can be thought of as donation of a lone pair from
the central atom into empty orbitals.
These were the important points in Chemical bonding. I
hope that these will help you. Always remember
CHEMISTRY IS EASY
THANK YOU.
Chemical bonding is a very important part of the syllabus and
plays an important role in understanding several other chapters
in inorganic chemistry. Further, IIT has often asked questions
on this and other related chapters.
Important Points:
1. ORBITAL OVERLAP
CONDITIONS FOR RESONANCE:
1. Identical arrangement of atoms.
2. Same number of unpaired electrons.
3. Similar energy content.
4. Planar.
5. Delocalisation.
FEATURES OF HYBRIDIZATION:
1. No of hybrid orbitals=No of atomic orbitals
2. Equivalent in shape and energy.
3. More effective in forming stable bonds.
4. Directed in space in a preferred direction to reduce repulsion.
CONDITIONS FOR HYBRIDIZATION:
1. Promotion of electron is not essential.
2. Both fully filled and half filled orbitals can take place in
hybridization.
HYDROGEN BONDING- CONSEQUENCES
1. Higher boiling points of H2O , NH3, HF.
2. Increase in melting point, boiling point,solubility and viscosity
of many compounds.
3. Viscosity of Phosphoric acid and Glycerol.
4. Dimer formation in carboxylic acid and hexamer formation
in HF.
5. Negative azeotropy of mixtures of HF with water.
6. Ice is less dense than water - When water freezes, water
molecules form a crystalline structure maintained by hydrogen
bonding. The orientation of these bonds causes molecules in
ice to move apart from each other.
POLARIZATION:
1. Cation should be small and anion should be large.
2. Both should have high charge.
3. Cations with pseudo inert config have higher polarizing
power.
4. Pseudo > non inert > inert
5. Polarization is proportional to acidic character.
6. Polarization is proportional to color intensity.
VSEPR THEORY:
MOLECULAR ORBITAL THEORY
MISCELLANEOUS POINTS:
1. More electronegative element prefers to stay at axial
position whereas lone pair prefers to stay at equatorial
position( only for TBP).
2. % of p character is proportional to length and thinness of
bonds.% of s character is proportional to repulsion.
3. The more electronegative element prefers to stay in the
orbital having more p character and it also increases p
character in the attached orbital.
eg. In CH2F2 the C-F bond has more p character and is
longer than C-H bond. Hence C-H bonds repel each other
more and H-C-H bond angle is greater than F-C-F.
4. Back bonding: In molecules like NCl3 and Cl2O, the bond
angle is greater than expected. This is due to back bonding
which can be thought of as donation of a lone pair from
the central atom into empty orbitals.
These were the important points in Chemical bonding. I
hope that these will help you. Always remember
CHEMISTRY IS EASY
THANK YOU.
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