Formal Charges
Formal charges have an important role in organic chemistry since this concept helps us to know whether an atom in a molecule is neutral/bears a positive or negative charge. Even if some molecules are neutral, the atoms within that molecule need not be neutral atoms.
Polarity Of Water
In simple chemical terms, polarity refers to the separation of charges in a chemical species leading into formation of two polar ends which are positively charged end and negatively charged end. Polarity in any molecule occurs due to the differences in the electronegativities of the bonded atoms. Water, as we all know has two hydrogen atoms bonded to an oxygen atom. As oxygen is more electronegative than hydrogen thus, there exists polarity in the bonds which is why water is known as a polar solvent.
Valence Bond Theory Vbt
Valence bond theory (VBT) in simple terms explains how individual atomic orbitals with an unpaired electron each, come close to each other and overlap to form a molecular orbital giving a covalent bond. It gives a quantum mechanical approach to the formation of covalent bonds with the help of wavefunctions using attractive and repulsive energies when two atoms are brought from infinity to their internuclear distance.
Based on periodic trends in electonegativity, which of the following bonds is expected to be MOST polar?
| A. |
H-F |
|
| B. |
C-C |
|
| C. |
N-O |
|
| D. |
C-H |
|
| E. |
C-O |
More is the electronegativity difference between the atoms making bond, more will be the polarity of the bond.
Since the electronegativity of H is much less than F.
Hence the electronegativity difference will be very high in H-F bond.
Hence H-F will be highly polar.
Now since the electronegativity of C is less than F. Hence the electronegativity difference in C-H bond will be less than H-F bond
And since there is no electronegativity difference in C-C bond. Hence the bond will be non polar
Hence the H-F bond is more polar than C-F bond and C-C bond
Now among C-O and N-O bond, since the electronegativity order of atoms is C < N < O
Hence the electronegativity difference between C-O will be more than N-O bond
Hence N-O bond will be more polar than C-O
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