Bond Parameters MCQ Quiz in मल्याळम - Objective Question with Answer for Bond Parameters - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Concept:

Dipole moment:

• It is a vector quantity that gives a measure of the polarity of the bond.
• It arises due to differences in the electronegativities of the constituent atom of a chemical bond.
• Since it is a vector quantity it has both magnitudes as well as direction.
• The dipole moment in a molecule can be zero as it is a vector quantity, two opposite dipoles can cancel each other.
• The direction of the dipole moment is shown with the help of an arrow.
• Dipole moment of a molecule having a number of atoms is the vector sum of all the dipoles present in the molecule.

Explanation:

The dipole moment of a molecule is the vector sum of all the dipoles present in the molecule.

→ BF₃

• BF₃ has sp² hybridisation and trigonal planar geometry.
• In its structure, it has three σ bonds (B-F), separated by 120° each.
• As the dipole moment in a molecule is the vector sum of all dipoles present in the molecule, the BF₃ molecule is having zero dipole moment.

→ Dipole moment of NH₃ and NF₃ -

• Both NH₃ and NF₃ have sp³ hybridisation and trigonal pyramidal shape.
• Both are having one lone pair each.
• But there is a difference in electronegativities of Hydrogen and Fluorine.
• In the case of NH₃, the dipole moment due to the N-H bond and due to the lone pair are in the same direction.
• But in the case of NF₃, the dipole moment due to N-F bonds are opposite to the direction of the dipole moment due to the lone pair. Thus, it is having a lesser dipole moment than NH₃.
• The dipole moment of NH₃ is greater than NF₃.

→ Dipole moment of H₂O -

• Oxygen is more electronegative than Hydrogen.
• It has two lone pairs.
• All dipole moments are in the same direction.
• It has a dipole moment greater than NH₃ due to having more number of lone pairs and also the electronegativity of oxygen is greater than nitrogen.
• Hence, H₂O has more dipole moment than NH₃.

So, the order of dipole moment in the above molecules is -

∴ The correct answer is option (3).

Isoelectronic species :

• Those species having the same number of electrons but differ in nuclear charge are called isoelectronic species.
• Example: Mg2+, Na+, F–, and O2–  have 10 electrons each so they are isoelectronic.
• But, their radius is different due to differences in nuclear charges. 
• Ionic radius decreases along a period for Isoelectronic ions.

​Isostructural species:

• The species which have different atoms or elements in them but have the same hybridization and structure are called isostructural species.
• Examples are NF3 and NH3, they have both sp3 hybridization and pyramidal shape.

Explanation:

• The species and their structures and number of electrons are given below:

• From the table above we see that CH3-, NH3, H3O+ all have 10 electrons in them.
• Hence, they are isoelectronic species.

Thus the correct option is II, III, IV.

CONCEPT:

Formal Charge:

• Formal charge on any polyatomic molecule can be assigned by assuming that, electrons in all bonds are shared between constituent atoms regardless of electronegativity difference among the atoms.
• Mathematical expression of formal charge is as follow,

Where, V= number of valence electrons of atom in its free/ground state

             N= number of non-bonding valence electrons on the atom in molecule

             B= total number of electrons shared in bonds with other atoms in the molecule

EXPALANTION:

Phosphate ion:

• Phosphate ion consist of central P atom, surrounded by four oxygen atoms in tetrahedral arrangement.
• Phosphate ion consist of (-3) formal charge.

• Resonance structure of phosphate ion is as follow:

• Here. Phosphate form a double bond with one oxygen and a single bond with the other three oxygen atoms.
• Formal Charge on oxygen atom that forms a single bond with phosphate,

V= six valence electrons for oxygen atom.

N= six non-bonding electrons for oxygen atom

B= two electrons for the P-O bond

CONCLUSION:

The correct option is (2). The formal charge on the oxygen atom is -1, for the P-O bond.

Concept: 

Dipole moment: 

• Dipole moment arises in a polar bond be it ionic or covalent.
• The greater the separation of charges between the atoms in bonds, the greater is the value of the dipole moment.
• The magnitude of the dipole moment is measured in unit Debye.
• The direction of the dipole in a bond is towards the more electronegative atom.
• Dipole moment is a vector quantity. It has a magnitude as well as direction.

The value of the dipole moment of a bond depends on:

• The difference in electronegativity of the atoms.
• The distance between the atoms.

\(\mu = q × r \)

The relation between percentage ionic character and bond dipole moment is:

\(\% \;{\bf{Ionic}}\;{\bf{character}}\; = \frac{{\mu \_obs}}{{\mu \_cal}}100\)

Calculation:-

µ = q x r 

⇒ q = 1.6 x 10-19 C, r = 3 x 10-10 m,

thus µ = q x r  = 1.6 x 10-19 x 3 x 10-10 = 4.8 x 10-29. 

In standard unit of µ =  4.8 x 10-29/ 3.336 x 10-30 = 1.43 x 10 1 = 14.3 D.

Percentage of Ionic character is calculated by Ionic character = Expected Value / Theoratical Value x 100

⇒ 10.8 D / 14.3 D x 100 = 75.5 percent. 

Concept:

Electronegativity - Electronegativity is the ability of an atom to attract a shared pair of electrons toward itself.

• The value of electronegativity increases as we move from left to right in a period.
• The value of electronegativity decreases as we move down in a group.
• Fluorine is the most electronegative element.
• Caesium is the least electronegative element.
• If the difference in electronegativity of bonded atoms is > 1.7  the bond will be ionic and if it is in the range of 0.4 to 1.7 then the bond will be covalent in nature.

Explanation:

Variation of electronegativity in a period:

• Electronegativity increases as we move from left to right in a period.
• In the period, nuclear charge increases but the number of outermost shells remains the same.
• Thus, the size of the atom decreases, and the ability to attract shared pair of an electron increases.

∴ The value of electronegativity increases from Li → F in 2nd period.

Variation of electronegativity in a group:

• Electronegativity decreases as we move down in the group.
• In a group, the atomic number of elements increases along with the increase in the number of shells as we move down the group, and the overall effect is the increasing number of shells of atoms as we move down.
• Hence, the size of the atom increases, and the ability to attract shared pairs of electrons decreases as we move down the group.

∴ The value of electronegativity increases from F → I in group 17.

or

The most electronegative element in the periodic table is Fluorine.

Conclusion:

Therefore, the electronic configuration of the outermost shell of the most electronegative element is 2s22p5 (∵ fluorine (1s²2s22p5) is the most electronegative atom).

Hence, the correct answer is option 1.

Additional Information  Factor affecting electronegativity:

1. Size of an atom - Electronegativity increases with a decrease in the size of the atom.
2. Nuclear charge- A greater nuclear charge will result in a large electronegativity value.
3. Presence of substituent - Electronegativity value depends upon the nature of the substituent attached to that atom.

Correct answer: 2)

Concept:

• The ionization energy is the quantity of energy that an isolated, gaseous atom in the ground electronic state must absorb to discharge an electron, resulting in a cation.
• H(g)→H⁺(g) + e⁻
• This energy is usually expressed in kJ/mol, or the amount of energy it takes for all the atoms in a mole to lose one electron each.

Explanation:

• Ionization enthalpy decreases on moving from top to bottom in the periodic table or in a group and Ionization enthalpy increases on moving from left to right in a row of the periodic table. 
• The elements which are having half-filled and fully-filled orbitals in electronic configuration have more ionization energy than the value observed in periodic trends. 
• Here, among the given options,  in [Ne] 3s²3p³, 'p' orbital is half-filled.
• Outermost electronic configuration 3s²3p³.
• So it has the highest ionization energy among the options.

Conclusion:

Thus, the electronic configuration [Ne] 3s2 3p3 will have the highest ionization energy.

Concept:

Dipole moment (μ) - 

• Dipole moment gives the polarity or ionic character of a chemical bond between two atoms in a molecule.
• Dipole moments occur due to difference in the electronegativity of the bonded atoms.
• Dipole moment is a vector quantity so, it has both magnitude as well as direction.
• The separation of charges thus arises due to polarity is shown by the symbols δ^- and δ⁺.

Formula to calculate dipole moment(μ ) = δ × d

where, δ is the magnitude of partial charges and 'd' is the distance between the charges. 

Explanation:

• In ortho-, meta-, para- dichlorobenzene the bond angle of C-Cl is 60°, 120°, and 180° respectively.   
• Thus, the net dipole moment in the case of p-dichlorobenzene is zero due to the symmetrical structure.
• The bond angle is inversely related to dipole moment, and o-dichlorobenzene has lower C-Cl bond angle thus, having higher dipole moment than m-dichlorobenzene.
• Further, the electronegativity of chlorine is more than -CH₃ group, thus, toluene is having less dipole moment than o-, and m-dichlorobenzene.

Therefore the overall order of dipole moment in given molecules is -

o-dichlorobenzene > m-dichlorobenzene > toluene > p -dichlorobenzene.

Conclusion:

The correct increasing order of dipole moment of the following compounds is - (iv) < (i) < (ii) < (iii).

The correct answer is Benzimidazole

Concept:-

• Isoelectronic Definition: Understanding that isoelectronic molecules have the same number of electrons, which is crucial in identifying the correct structure.
• Aromaticity: Recognizing the aromatic nature of naphthalene, which has two fused benzene rings, and applying this concept to select a molecule with a similar structure.
• Heterocyclic Rings: Identifying the presence of heterocyclic rings (imidazole) in benzimidazole and understanding their role in maintaining isoelectronicity.

Explanation:-

• Naphthalene is a polycyclic aromatic hydrocarbon with two fused benzene rings. A molecule is isoelectronic with another when it has the same number of electrons. For naphthalene (C₁₀H₈), a molecule with the same number of electrons would be isoelectronic.
• 
• Among the given options, Benzimidazole is isoelectronic with naphthalene. Benzimidazole has a fused benzene ring and an imidazole ring, providing the same number of electrons as naphthalene.
• 
• Both naphthalene and benzimidazole have a fused benzene ring, contributing to their isoelectronic nature. Benzimidazole has additional heteroatoms (nitrogen) in the imidazole ring, maintaining the overall electron count.

Conclusion:-

So, Benzimidazole is isoelectronic with naphthalene, sharing a similar structure with a fused benzene ring and additional heterocyclic rings.

CONCEPT:

• A dipole moment occurs in any molecule in which there is a separation of charges.
• A dipole moment generates in ionic bonds as well as in covalent bonds.
• Dipole moments arise due to the difference in electronegativity between two bonded atoms.
• A bond dipole moment is a measure of the polarity of a chemical bond between two atoms in a molecule.
• The bond dipole moment is a vector quantity since it has both magnitude and direction.
• For example,
• Mathematically dipole moment can be expressed μ = 𝛿 d

                      Where, μ = bond dipole moment

                                   𝛿 = magnitude of the partial charges 𝛿+ and 𝛿–

                           And d = distance between 𝛿+ and 𝛿– (bond length)

• It is measured in the Debye unit denoted by ‘D’.
• The larger the electronegativity difference between the two atoms, the larger the bond’s dipole moment and polarity.

EXPLANATION:

Case-1 CO₂:

• Carbon dioxide has a linear geometry.
•  Carbon atom at the centre and oxygen on both sides.
• Electronegativity values of carbon and oxygen are 2.5 and 3.5, hence the difference is nearly equal to 1.
• Oxygen is more electronegative than carbon atoms hence electron density between the

          the C-O bond is near the oxygen atom.

• Here, oxygen atoms on both sides have the same tendency, so the dipole moment that arises in both C-O bonds is equal and in opposite directions. Hence net dipole moment is zero.

Case-2 HI:

• HI is a linear molecule.
• Electronegativity values of hydrogen and iodine are 2.2 and 2.66, hence the difference is small. And hence dipole moment is low.

Case-3 H₂O:

• Water is a V-shaped molecule (bent).
• Electronegativity values of hydrogen and oxygen are 2.2 and 3.5, hence the difference is larger than 1.

• Electronegativity difference is high for the water molecule, hence higher the dipole moment.

Case-4 SO₂:

• Sulphur dioxide is a V-shaped molecule (bent).
• Electronegativity values of sulphur and oxygen are 2.5 and 3.5, hence the difference is equal to 1.
• Electronegativity difference is high for sulphur dioxide molecules, hence higher the dipole moment.

CONCLUSION:

• The electronegativity difference is higher for water molecules compare to SO₂. HI has a lower dipole moment compared to SO₂ and CO₂ has a zero dipole moment.

CONCEPT:

• A dipole moment occurs in any molecule in which there is a separation of charges.
• A dipole moment generates in ionic bonds as well as in covalent bonds.
• Dipole moments arise due to the difference in electronegativity between two bonded atoms.
• A bond dipole moment is a measure of the polarity of a chemical bond between two atoms in a molecule.
• The bond dipole moment is a vector quantity since it has both magnitude and direction.
• For example,
• Mathematically dipole moment can be expressed μ = 𝛿 d

                      Where, μ = bond dipole moment

                                   𝛿 = magnitude of the partial charges 𝛿+ and 𝛿–

                           And d = distance between 𝛿+ and 𝛿– (bond length)

• It is measured in the Debye unit denoted by ‘D’.
• The larger the electronegativity difference between the two atoms, the larger the bond’s dipole moment and polarity.

EXPLANATION:

Case-1 CO₂:

• Carbon dioxide has a linear geometry.
•  Carbon atom at the centre and oxygen on both sides.
• Electronegativity values of carbon and oxygen are 2.5 and 3.5, hence the difference is nearly equal to 1.
• Oxygen is more electronegative than carbon atoms hence electron density between the

          the C-O bond is near the oxygen atom.

• Here, oxygen atoms on both sides have the same tendency, so the dipole moment that arises in both C-O bonds is equal and in opposite directions. Hence net dipole moment is zero.

Case-2 HI:

• HI is a linear molecule.
• Electronegativity values of hydrogen and iodine are 2.2 and 2.66, hence the difference is small. And hence dipole moment is low.

Case-3 H₂O:

• Water is a V-shaped molecule (bent).
• Electronegativity values of hydrogen and oxygen are 2.2 and 3.5, hence the difference is larger than 1.

• Electronegativity difference is high for the water molecule, hence higher the dipole moment.

Case-4 SO₂:

• Sulphur dioxide is a V-shaped molecule (bent).
• Electronegativity values of sulphur and oxygen are 2.5 and 3.5, hence the difference is equal to 1.
• Electronegativity difference is high for sulphur dioxide molecules, hence higher the dipole moment.

CONCLUSION:

• The electronegativity difference is higher for water molecules compare to SO₂. HI has a lower dipole moment compared to SO₂ and CO₂ has a zero dipole moment.