Bonding Concepts in Organic Compounds - Conceptual Questions

1. Explain the concept of formal charges.
2. Explain the concepts of electronegativity and polarity.
3. What are atomic orbitals and molecular orbitals?
4. What are bonding and antibonding orbitals?
5. Where do you find sp3, sp2 and sp hybridization bonds?
6. Explain the concept of resonance.
7. What are the rules for writing resonance structures?
8. Explain various concepts of acids and bases.
9. Explain the concepts of conjugate base and conjugate acid.
10. Explain the concepts of acidity constant.
11. What the effect of following structural aspects on the strength of acids and bases?
a. inductive effects
b. effect of the atom bonded to the hydrogen
c. resonance
d. hydrogen bonding
e. hybridisation

Application Questions Ch. 5 Bonding

Understand the following statements

1. CuSO4 has ionic, covalent and coordinate bonds
2. SO2 involves sp2 hybridization
3. HgCl2 and C2H2 are linear molecules
4. CH3+ has sp2 hybridization
5. SO2, NO2 and ClO2 are not linear while CO2 is linear.
6. NCO- has linear structure.
7. In ClO2- chlorine atom has sp3 hybridization
8. In OF2 oxygen atom will have sp3 hybridization.
9. N2O4 has covalent and coordinate bonds
10. Molecular oxygen has unpaired electrons.
11. NO3- has sp2 hybridization.
12. NO2+ has sp hybridization


MCQs

1. Which of the of following do not exhibit both ionic and covalent bond.
a) BaSo4
b) NH4Cl
c) Ca(NO3)2
d) HCl

2. Which of the following has maximum covalent character?
a) LiI
b) LiF
c) LiCl
d) LiBr

Past JEE Questions Ch.5 Bonding and Molecular Structure

1991
The linear structure is not assumed by
a) SnCl2
b) CS2
c) NO₂⁺
d) HCN

Answer a

1992
The molecule that will have no dipole meet is:
a) 2,2-dimethyl propene
b) Trans 2-pentene
c) cis-3-hexane
d)2,2,3,3,-tetramethylbutane

ans: d

1993

Which of the following has zero dipole moment?
a) CLF
b) PCl3
c) SiF4
d) CFCl3

ans: c

1995

Which is most ionic?
a) P2O5
b) MnO
c) CrO3
d) Mn2O7

b


1996
The number and type of bonds between two carbon atoms in calcium carbide are

a) one σ , one π
b) one σ, two π
c) two σ , one π
d) one σ, 1½ π

Ans: b

1997
Which one of the following compounds has sp² hybridization
a) CO2
b) SO2
c) N2O
d) CO

ans: b

1998
The geometry and type of hybrid orbital present about the central atom in BF3 is

a) linear, sp
b) trigonal planar, sp^2
c) tetrahedral, sp^3
d) pyramidal, sp^3

ans: b

1999
The geometry of H2S and its dipole moment are:
a) angular and non-zero
b) angular and zero
c) linear and non-zero
d) linear and zero


2000 screening
Molecular shapes of SF4, CF4, and XeF4 are
a) the same with 2,0,1 lone pairs of electrons respectively
b) the same with 1,1,1,lone pairs of electrons respectively
c) different with 0,1,and 2 lone pairs of electrons respectively
d) different with 1,0, and 2 lone pairs of electrons respectively

ans: d

2001 screening
The correct order of bybridization of the central atom in the following species: NH3, [PtCl4]^2-, PCl5 and BCl3 is

a) dsp^2, dsp^3, sp^2, and sp^3
b) sp^3, dsp^2,dsp^3,sp^2
c) dsp^3,sp^2,sp^3,dsp^3
d) dsp^2,sp^3,sp^2,dsp^3

ans: b

Among the following, the molecule with the highest dipole moment is:

(A) CH-3Cl (B) CH-2Cl-2
(C) CHCl-3 (D) CCl-4

answer A
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JEE Question 2007 paper I

The percentage of p-character in the orbitals forming P–P bonds in 4 P is
(A) 25
(B) 33
(C) 50
(D) 75
Solution: (D)

Phosphorous will show sp^3 hybridisation having 75% p-character.
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JEE Question 2007 paper I

Statement - 1

Boron always forms covalent bond

Because

Statement - 2

The small size of B3^+ favours formation of covalent bond.

(A) Statement – 1 is True, Statement – 2 is True; Statement – 2 is a correct explanation for statement – 1
(B) Statement – 1 is True, Statement – 2 is True; Statement – 2 is Not a correct explanation for Statement – 1.
(C) Statement – 1 is True, Statement – 2 is False
(D) Statement – 1 is False, Statement – 2 is True

Answer: A

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JEE Question paper II 2007

Among the following metal carbonyls, the C — O bond order is lowest in
(A) [Mn(CO)-6]^+

(B) [Fe(CO)-5]
(C) [Cr(CO)-6]
(D) [V(CO)-6]^-


answer: B
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JEE 2006

If the bond length of CO bond in carbon monoxide is 1.128 A,
then what is the value of CO bond length in Fe(CO)-5?
(A) 1.15 A
(B) 1.128 A
(C) 1.72 A
(D) 1.118 A


Answer: (A)
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IIT JEE Chemistry Questions Ch.5. BONDING AND MOLECULAR STRUCTURE

Orbital overlap and covalent bond;
Hybridisation involving s, p and d orbitals only;
Orbital energy diagrams for homonuclear diatomic species;
Hydrogen bond;
Polarity in molecules, dipole moment (qualitative aspects only);
VSEPR model and shapes of molecules (linear, angular, triangular, square planar, pyramidal, square pyramidal, trigonal bipyramidal, tetrahedral and octahedral).

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Theory Questions

Orbital overlap and covalent bond;
1. State the octet rule?
2. What are the instances where octet rule was found inadequate?
3. What is covalent bond?
4. What is coordinate covalent bond?
5. Name some molecules of having same atoms that have double bond.
6. Name some molecules of having same atoms that have triple double bond.
7. Name some compounds where N atom does not complete it octet.
8. do covalent bonds have directional character.
9. what is a coordinate bond?
10. give some examples of molecules having coordinate bonds.


Hybridisation involving s, p and d orbitals only;
1. Explain the need for the concept of hybridization?
2. Exlain the concept of hybridization.
3.

Orbital energy diagrams for homonuclear diatomic species;


VSEPR model and shapes of molecules (linear, angular, triangular, square planar, pyramidal, square pyramidal, trigonal bipyramidal, tetrahedral and octahedral).

1. What is VSEPR formulated? What does it try to explain?
2. What are the postulates of VSEPR theory?
3. What is the strength of repulsive forces over various possible pairs of electrons?
4.Why there are distortions in certain molecules from standard geometrical shapes indicated by the number of electron pairs?
5. Give examples of molecules that have linear arrangement of atoms.
6. Give examples of molecules that have trigonal planar arrangement of atoms.
7. Give examples of molecules that have tetrahedral arrangement of atoms.
8.Give examples of molecules that have trigonal bipyramidal arrangement of atoms.
9. Give examples of molecules that have octahedral arrangement of atoms.
10. Give examples of molecules that have pentagonal bipyramidal arrangement of atoms.
11. Give the geometrical shapes for molecules havng 2 to 7 electronic pairs around the central atom in a molecule.


Polarity in molecules, dipole moment (qualitative aspects only);


Hydrogen bond;


Concepts

1. State the octet rule?
2. What are the instances where octet rule was found inadequate?
3. Give important features of valence bond theory.
4. give different overlaps between 's' and 'p' orbitals and also give one example of each.
5. Explain the need for the concept of hybridization?
6. Exlain the concept of hybridization.
7. Explain the formation of sigma bond.
8.Explain the formation of pi bond.
9. Define bond energy?
10. What is ionic bond?
11. What is covalent bond?
12. What is coordinate covalent bond?


Applications and Examples

1. Why is H-F bond polar?
2. Give the geometry of hyubridised orbital in the following compounds.
a. Methane
b. water
c. ethyne
d. Boron trifluoride
e. Ammonia
f. BeF-2
g. ethene

3. Why bond angle in ammonia molecule is less than the expected tetrahedral bond angle?
4. There is only one pi-bond in ethylene molecule but here are two pi-bonds in the acytylene moecule. Explain.
5. Why a sigma bond is stronger than pi-bond?
6. The bond energy of PCl-3 is larger than the bond energy ni PCl-5. Why?
7. Bond energy in HF is larger than HI. Why?
8. Why H-O-H bond angle in water molecule is reduced to 104° 35'?