Class 11 Medical Chemistry - Chemical Bonding And Molecular Structure

The structure of a peptide is given below.
If the absolute values of the net charge of the peptide at $pH = 2, pH = 6$ and $pH = 11$ are $|z_1|, |z_2|,$ and $|z_3|$ , respectively, then what is $|z_1|+|z_2| + |z_3| ?$

Therefore

$|z_1| + |z_2| + |z_3| = 2 + 0 + 3 = 5$

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What is meant by the term chemical bond and chemical bonding?

Atoms of different elements excepting noble gases do not have complete octet so they combine with other atoms to form chemical bond.

The force which holds the atoms or ions together within the molecule is called a chemical bond and the process of their combination is called chemical bonding.

The covalency of sulphur in the sulphur molecule ( $S_8$ ) is :

From the figure given below, it can be seen that oxidation number of

$S$ in

$S_8$ is zero (elemental form) and co-valency is

$2$ .

Total number of the sigma bonds present in benzene ring are:

In benzene, there are 6 (C-C) sigma bonds and 6 (C-H) sigma bond. Thus, the total number of sigma bonds is 12.
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__________ overlapping between orbitals leads to $\pi$ bond formation.

$\pi$ bonds are always formed by sidewise overlaping while sigma bond is formed by axial end to end overlap

$1$ mole of $Na_2 S_2 O_3$ looses $10$ moles of $e^{-}$ . Determine final Oxidation number of S.

$Na_2S_2O_3$ in 2 x 1+2x 2+3x(-2)= 0

2 S makes =4

loses 10 electron so 6 e is from O and 4 is from S

S on is +4

Isotopes are the atoms of same element, with same atomic number. But with different __________.

Mass Number

Define isotopes.

Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number. All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

What are co-ordinate bonds?

A coordinate bond ( also called a dative covalent bond ) is a covalent bond ( a shared pair of electrons ) in which both electrons come from the same atom.

What is a lone pair of electrons?

A lone pair refers to a pair of valence electrons that are not shared with another atom and is sometimes called an unshared pair or non-bonding pair.

A certain mass of a gas occupies a volume of 2 L at STP. To what temperature the gas must be heated to double its volume, keeping the pressure constant?

How many lone pair of electrons are present on the central atom of $CH_4, H_2O, NH_3, PCl_3$ and $PCl_5$ molecules?

Draw the lewis dot structure of each compound.

What types of overlapping take place in a sigma and a pi bond?

Overlapping of s - s, s - p and axial overlapping of p - p results in

$\sigma$ . Sideways overlapping of p - p results in

$\pi$ bond.

Total number of lone pair of electrons on $Xe$ in $XeOF_{4}$ is ________.

It has one lone pair of electron. It has 6 pairs in the valence shell of Xe, thus it shows,

$sp^3d^2$ hybridization.

By using an expanded octet for the sulphur atom in thionyl chloride (SOCl $_{2}$ ), you can write a Lewis structure with no formal charge.
If true enter 1 else 0

Formal charge = valence electrons

$\frac{bonding electrons}{2}$ - lone pair electrons
Oxygen = 6 -

$\frac{4}{2}$ -4 = 0
Sulphur = 6 -

$\frac{8}{2}$ -2 = 0
Chlorine = 7 -

$\frac{2}{2}$ -6 = 0

If true enter 1, else enter 0.
When ethene reacts with $H_2$ , ethane is formed. The $\pi$ bond of C=C is affected. Thus, $\pi$ bond is more reactive than $\sigma$ -bond.

As pi-bonds are weaker in strength than sigma bonds, the pi-bond in an alkene breaks easily and they are more reactive than sigma bonds.

Consider the following Lewis Dot structure:

$\left[: \ddot{N} = N = \ddot{N}:\right]^-$

The formal charge on the central $N$ atom is:

Formal Charge = [valence electrons on atom] - [non-bonded electrons + number of bonds].

$N$ (central)=

$5-[0+4]=+1$

$N$ (terminal)=

$5-[4+2]=-1$

$HONO$ ?

[Note: single bond contain

$1 \sigma$ bond and double bond contain

$1 \sigma$ and

$1 \pi$ bond.]
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Consider the following Lewis Dot structure:

$\left[: \ddot{O} = N = \ddot{O}:\right]^+$

The sum of formal charges on $N$ and $O$ is:

Formal Charge = [valence electrons on atom]

$-$ [non-bonded electrons + number of bonds].

Formal charge on

$N=5-[0+4]=+1$

Formal charge on

$O=6-[4+2]=0$

Therefore, the sum of the formal charges on

$N$ and

$O$ atoms is

$= 1+0=1$

So, the correct answer is

$1$

$H_2N-OH$ ?

The Lewis structure of

$H_2N-OH$ is given by-

$H-\overset{..}{\underset{H}{\underset{|}{N}}}-\overset{..}{\underset{..}{O}}-H$

There are

$4\sigma$ bonds in the molecule.

How many $\sigma$ bonds are present in $H_2N-NO_2$ ?

On looking at the lewis structure, it is clear that the molecule has 5 sigma bonds.

Formal charge on sulphur in $SO_2$ is:

$S$ atom has six valence electrons out of which

$2$ remain as lone pair of electrons and

$4$ are shared with

$2$ oxygen atoms to form covalent bonds.
Hence, neither an electron is gained nor it is lost. Hence, neither negative nor positive charge is present on

$S$ atom.
Hence, the formal charge on

$S$ atom in

$SO_2$ is zero.

Out of $CH_2Cl_2, CH_4, CCl_4, H_2O, CHCl_3, d-$ dichlorobenzene, $o$ -cresol, $p$ -xylene, $SCl_2, BF_3, IBr$ and $CH_2O$ , non zero value of dipole moment are:

The compounds

$CH_2Cl_2, H_2O, CHCl_3, o$ -cresol,

$SCl_2, IBr$ and

$CH_2O$ have non zero value of dipole moment.
Thus total seven compounds have non zero dipole moment. In these molecules, the individual bond dipoles do not cancel each other. Hence, the net dipole moment of the molecule is non zero.

The compounds

$\displaystyle CH_4$ ,

$\displaystyle CCl_4$ , p-dichlorobenzene, p-xylene and

$\displaystyle BF_3$ have zero dipole moment as the individual bond dipoles cancel each other.

Numbers of geometric isomers of $PBr_2Cl_3$ molecule which have non-zero dipole moment are:

Numbers of geometric isomers of

$PBr_2Cl_3$ molecule which have non-zero dipole moment are 2.

Ratio of bond pair-lone pair electrons $XeO{F}_{2}$ is:

$XeO{F}_{2}$ has

$4$ bond pairs of electrons and

$2$ lone pairs of electrons.
Hence, the ratio of bond pair-lone pair electrons is two.

Maximum number of atoms which can be attached on $N$ -atom are :

Maximum number of atoms which can be attached on N-atom are four.
Thus the maximum valence of N is 4. An example includes ammonium ion.

$NH_4^+$ .
The answer is 4.

If true enter 1, else enter 0.
Hydrogen bond is weaker than a covalent bond.

Hydrogen bond is weaker than a covalent bond.
A covalent bond is formed when two atom share a pair of electrons.
A hydrogen bond is a type of dipole - dipole interaction. It is the electrostatic force of attraction between H atom having partial positive charge and more electronegative atom (N, O or F) having partial positive charge.

If the statement is true enter 1, else enter 0.

Repulsion between bond pair-bond pair electron is lesser than in between lone pair-lone pair.

Repulsion between bond pair-bond pair electron is lesser than in between lone pair-lone pair.

The correct order of the repulsion is

$lp-lp > lp-bp>bp-bp$

Number of Sugden's singlet bonds in $P{Cl}_{5}$ is :

Sudgen supported the theory of octet rule by saying that the Concept of octet can never be disobeyed as was overruled by SIDGEWICK by announcing the maximum rule of co-valency. Sudgen took into account the example of phosphorous pentachloride and told that out of five bonds two are singlet i.e., made by sharing of one electron between two atoms donated by only one participent. in short it is the bond consisting only on one electron and is relatively longer than a covalent bond and is known as half covanlent bond.

If true enter 1, else enter 0.
The $H$ -bond energy is around $8.4kJ$ ${mol}^{-1}$ .

The

$H-H$ bond dissociation energy is about

$436 kJ/mol$ or

$104.5 kcal/mol$ .

Number of unpaired electrons in ${O}_{2}[As{F}_{4}]$ is :

Most stable oxidation state of As is +3.

${ O }_{ 2 }[As{ F }_{ 4 }]$ can be divided as

${ O }_{ 2 }^{ + }$ and

${ [As{ F }_{ 4 }] }^{ - }$ . Now we will find number of unpaired electrons in

${ O }_{ 2 }^{ + }$ i.e., equal to 1 as we can see below with th help of its electronic configuration:

${ ({ \sigma }_{ 1s }) }^{ 2 }<{ ({ \sigma }_{ 1s }^{ * }) }^{ 2 }<{ ({ \sigma }_{ 2s }) }^{ 2 }<{ ({ \sigma }_{ 2s }^{ * }) }^{ 2 }<{ ({ \sigma }_{ 2{ p }_{ z } }) }^{ 2 }<{ ({ \Pi }_{ 2{ p }_{ x } }) }^{ 2 }={ ({ \Pi }_{ 2{ p }_{ y } }) }^{ 2 }<{ ({ \Pi }_{ 2{ p }_{ x } }^{ * }) }^{ 1 }$

In acetylene, there are ______ (two/four) $\pi$ - bonding electrons between carbon atoms.

The structure of Acetylene is:

$(CH\equiv CH)$

It contains two

$\pi$ -bonds and each

$\pi$ - bond contains two

$\pi$ bonding electrons. So a total of four

$\pi$ bonding electrons are present in acetylene.

So, the correct answer is 4.

The dipole moment of ${CH}_{3}OH$ ____ (more/less) than that of ${CH}_{3}SH$

Oxygen has more electronegativity than

$S$ . This makes the

$C-O$ bond more polar than the

$C-S$ bond.

So, the dipole moment of

${ { { CH }_{ 3 }OH }^{ } }_{ }$ is more than

$CH_3SH$

The number of lone pairs of an electron on central iodine atom of ${I}_{3}^{-}$ ion is:

1155456_200657_ans_123d79f400924215af16cebc7c99188e.png

Find the number of lone pairs of electrons on $Xe$ in $XeOF_4.$

One lone pair of electrons is present on Xe in

$XeOF_4.$

$Xe$ has eight valence electrons out of which four are shared with

$4$ electrons of

$4\: F$ atoms.

$2$ electrons of

$Xe$ are shared with

$2$ electrons of

$O$ atom. Thus, only one lone pair of electrons is remaining on

$Xe$ atom.

Find the ratio of the total number of bonds to the total number of lone pairs in $C_3N_3Cl_3$ .

There are

$12$ bonds and

$12$ lone pairs of electrons.
Hence, the ratio of the total number of bonds to lone pairs in

$C_3N_3(Cl_3)_3$ is

$\displaystyle \frac{12}{12}\, =\, 1$

Find the ratio of lone pairs to $\pi$ bond (present in ring).in $C_3N_3\, (NH_2)_3$ .

There are six lone pairs on each nitrogen (lp of nitrogen doesn't participate in resonance) and there are

$3$ pi bonds. So, their ratio is

$2$ .

Draw the electron dot structure of Ethanoic acid

The dot-structure of Ethanoic acid

Explain the nature of the covalent bond using the bond formation in $C{ H }_{ 3 }Cl$

Atomic number of C, H & Cl are 6, 1 & 17 respectively.
Their electronic configurations are
Carbon - 2, 4
Hydrogen - 1
Chlorine - 2, 8, 7
As C need 4 electrons to complete its octet, H needs 1 electron to complete its duplet and Cl needs 1 electron to complete its octet.
So, C share its 4 electron, one electron each with 3 H atom & 1 electron with Cl atom. Thus chloromethane contain 3 C-H - and one C-Cl covalent bond.
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In ${NO_3}^-$ ion, find the sum of bond pairs and lone pairs of electrons on nitrogen atom.

Nitrogen Atam - Bond pairs =

$4$

Lone pairs =

$0$

Total =

$4$ .

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1.

$O_3$ molecule, both covalent bond and co-ordinate bond are present.
In

$H_2O(l)$ molecule, covalent bond and Hydrogen bond are present.
In

$CuSO_4 . 5H_2O$ , covalent bond, co-ordinate bond, hydrogen bond and ionic bond are present.
In

$(NH_4)_2SO_4$ , covalent bond, co-ordinate bond and ionic bond are present.

Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms in $\displaystyle C_{2}H_{4}$ and $\displaystyle C_{2}H_{2}$ molecules.

In ethylene, the carbon atom is

$sp^2$ hybridized.
In acetylene, the carbon atom is

$sp$ hybridized.
The energy level diagrams of ethylene and acetylene are shown below.

What do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one example of each type.

Two atoms share one electron each to form a covalent bond.
The electrons present in the covalent bond are known as bond pair of electrons.
For example, in methane, there are four C-H covalent bonds.
Thus, in methane molecule, four bond pairs of electrons are present.
The electron pairs left in the valence shell without forming the bond are known as lone pairs of electrons.
For example, ammonia molecule has one lone pair of electrons and water molecule has two lone pairs of electrons.

Find the number of lone pairs and bond pairs in ${SF}_{6}$ .

According to the structure, there is no lone pair and 6 bond pairs.

Linear molecules possess _______ dipole moment.

Zero.

When molecule is linear, these two bond dipoles cancel each other out (i.e. the vector addition of the dipoles equals zero) and the overall molecule has a zero dipole moment

Lone pairs and bond pairs possess electrons. However, the repulsion experienced by lone pairs is much greater than that experienced by bond pairs. What reason can be attributed to this?

The lone pairs are localized on the central atom while the bond pairs electrons are shared between two atoms. The lone pairs of electrons in a molecule occupy more space as compared to the bonding pairs of electrons. This results in greater repulsion between lone pairs of electrons as compared to lone pair-bond pair and bond pair-bond pair repulsion.

In the formation of water molecule, _ number of lone pairs and number of bonds pairs are present.

In the formation of water molecule 2 lone pairs and 2 bond pairs are present.
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The number of bond pairs in the molecule $PCl_5$ is __________.

Total 5 bond pairs in the molecule

${ PCl }_{ 5 }$

1158185_522664_ans_6784279a6dfa43ebabe7221cab52d633.jpg

Why do only valence electrons involve in bond formation? Why not electron of inner shells? Explain.

Since inner electrons have very high Z-effective nuclear attraction. So only valence

${ e }^{ - }$ goes for bonding which has less Z-effective.

Explain the formation of sodium chloride and calcium oxide on the basis of the concept of electron transfer from one atom to another atom.

$\underbrace { Na\left( g \right) } \longrightarrow { Na }_{ \left( g \right) }^{ + }+\left( { e }^{ - } \right)$

one electron donor

$\downarrow \quad Cl\left( g \right)$

${ Cl }^{ - }\left( g \right)$

${ Na }^{ + }\left( g \right) +{ Cl }^{ - }\left( g \right) \longrightarrow NaCl\left( solid \right)$

$\underbrace { Ca\left( g \right) } \rightarrow { Ca }_{ \left( g \right) }^{ 2+ }+\left( { 2e }^{ - } \right)$

Two electron donor

$\downarrow \quad O\left( g \right)$

${ O }^{ 2- }\left( g \right)$

$\therefore \quad { Ca }^{ 2+ }\left( g \right) +{ O }^{ 2- }\left( g \right) \rightarrow CaO\left( solid \right)$

What is a Chemical bond?

Chemical bond is the attraction between two atoms to form chemical compounds. The chemical bond can be metallic, ionic or covalent.

Why water drops (dew) form on flowers and grass during morning hours of winter season ?

Dew drops are formed due to condensation of water vapours. Air around contains humidity or moisture. The presence of humidity is more in hot air as compared to cold air. During the night when this hot air comes in the contact with cold surface, the humidity condenses to form the droplets which we call as dew drops.

A, B, and C are three elements with atomic number 6, 11, and 17 respectively. Which of these can form an ionic bond as well as covalent bonds?

The atomic numbers 6, 11, and 17 corresponds to the C, Na, and Cl respectively.

Among the given elements, the chlorine has a tendency to form an ionic bond by gaining an electron and covalent bond by sharing of electrons.

Oxidation number of Cr in ${ K }_{ 3 }{ CrO }_{ 8 }$ is
(1) $+6$ (2) $+5$
(3) $+3$ (4) $+2$

The correct answer is 2

The structure of

$K_3CrO_8$ is tetragonal

Let oxidation number of Cr=x

$3+x+8\times (-2)$ =0

$3+x-16$ =0

x=+13

x=+5

Sbut since Chromium can have the maximum number +5 oxidation state. This contrary is solved by the bonding by bonding pattern as shown in structure. The Cr is attached to any 5 oxygen through a single bond. hence oxidation state is +5

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Calculate the fractional charge value of HCl the dipole moment is $1.02$ D.

The magnitude of dipole moment formed by two equal and opposite fractional charges

$+Q$ and

$-Q$ separated by a length

$l$ is given from

$M=Ql$

$\Rightarrow Q= \cfrac {M}{l}$

$\Rightarrow {1.020}{0.127 nm}= \cfrac {1.02\times 3.33564\times 10^{-30}m}{0.127\times 10 m}$

$=2.679 \times 10^{-20}$ coulombs.

Fractional charge value=

$0.167eV$

Which of the following molecules posses more dipole moment and why?
${ NH }_{ 3 }$ or ${ NF }_{ 3 }$

In $NH_3$ , N is more electronegative than H. So, N pulls the electrons from H towards itself and so the direction of the moment due to the N-H bonds is in the same direction as that of the lone pair of electrons on Nitrogen.

Whereas in $NF_3$ , the electronegativity of the F is more than N, thus the dipole moment of the bond pairs of electrons between N and F is towards F. But the dipole moment of the lone pair of electrons of N is opposite to the dipole moment of a bond pair.

So, $NH_3$ posses more dipole moment than that of the $NF_3$

What is the total number of sigma bonds and pi bonds in the following molecules?
$C_2H_3Cl$ , $CH_2Cl_2$ , $H_3C-\overset{H}{\overset{|}{C}}=\overset{H}{\overset{|}{C}}-C\equiv C-H$

${ C }_{ 2 }{ H }_{ 3 }Cl\Rightarrow H-\underset { | }{ C } =\underset { | }{ C } -Cl\ \Rightarrow \ 5\ \sigma \ bonds,\ 1\pi \ bond.\\ \quad \quad \quad \quad \quad \quad \ \ H\quad H$

${ CH }_{ 2 }{ Cl }_{ 2 }\Rightarrow Cl-\underset { | }{ C } =\underset { | }{ C } -Cl\ \Rightarrow \ 5\ \sigma \ bonds,\ 1\pi \ bond.\\ \quad \quad \quad \quad \quad \quad \quad H\quad H$

$\quad \quad \quad \ H\quad H\\ { H }_{ 3 }C-\overset { | }{ C } =\overset { | }{ C } -C\equiv C-H\ \Rightarrow \ 10\ \sigma \ bonds,\ 3\pi \ bonds$

Number of $\sigma$ bonds and $\pi$ bonds in methyl cyanide are $x$ and $y$ respectively. Value of $x+y$

No. of

$\pi$ bonds

$=2$

No. of

$\sigma$ bonds

$=5$

refer to image.

$x+y=2+5$

$=7$

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Explain the formation of a chemical bond.

Hint: A chemical bond is the mutual sharing of electrons between two or more than two atoms to complete its octet.

Explanation of answer:

The attractive force which holds together the constituent particles (atoms, ions or molecules) in a chemical species is known as chemical bond.

Atoms either share or gain or lose electrons to attain stable electronic configuration. Due to this, a state of minimum energy is obtained and chemical bond is formed.

When two atoms share electrons, covalent bond is formed and when atoms lose or gain electrons, ionic bond is formed. As shown below:

In above picture three covalent bond are formed by mutual sharing of electrons between two nitrogen atoms.

Here a complete transfer of electron form an ionic bond between two atoms.

Give reasons:
(i) ${BF}_{3}$ has zero dipole moment although the $B-F$ bonds are polar.
(ii) $NaCl$ is harder than $Na$ metal.

$(i)$ Resultant dipoles cancel out each other

$\therefore \quad Dipole moment=0$

$(ii)$

$NaCl$ is harder than

$Na$ because

$NaCl$ contain

${ Na }^{ + },Size:{ Na }^{ + }<Na$ , smaller the size more is hardness.

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How many bond pair and lone pair are there in $CO_3^{2-}$ ?

No. of bond pair

$=4$

$\because$ all

$4$ valence

${ e }^{ - }$ of

$C$ participated in bonding

No. of lone pair

$=8$

$\because$

$8$ pair of

${ e }^{ - }$ of oxygen did not participated in bonding.

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What is the dipole moment of $BeF_2$ molecule? Account for your answer.

$BeF_2$ structure $\longrightarrow F-Be-F$
It is a linear structure. Angle between the bond is $180^o$ .
The two bond dipole act in opposite direction and cancel out each other.

$F\underset {\longleftarrow}{-}Be\underset {\longrightarrow}{-}F$

Therefore, dipole moment in case of $BeF_2$ is zero.

What is the differnece between $\sigma$ and $\pi$ bonds?

$\underline{\sigma \text{ bond}}:$

$a.$ The bond is formed by the axial overlap of the atomic orbitals.

$b.$ A strong bond is formed.

$c.$ All the

$s-orbital$ and only one lobe of

$p-orbital$ is involved.

$d.$ The electron cloud is symmetrical.

$e.$ Free rotation about

$\sigma$ bond is possible.

$\underline{\pi\text{ bond}}:$

$a.$ The bond is formed by the sideways overlap of atomic orbitals.

$b.$ A weak bond is formed.

$c.$

$s-orbital$ do not take part, while both lobes of

$p$ take part.

$d.$ The electron cloud is unsymmetrical.

$e.$ Free rotation of atom around

$\pi$ -bond is not possible.

Compare and justify the dipole moment of ${ NH }_{ 3 }$ and ${ NF }_{ 3 }.$

The net dipole moment of

$N{F}_{3}$ is less than that of

$N{H}_{3}$ .

In both molecules i.e.,

$N{H}_{3}$ and

$N{F}_{3}$ , the central atom

$\left( N \right)$ has a lone pair electron and there are three bond pairs. Hence, both molecules have a pyramidal shape.

Since fluorine is more electronegative than hydrogen, it is expected that the net dipole moment of

$N{F}_{3}$ is greater than

$N{H}_{3}$ . However, the net dipole moment of

$N{H}_{3}$ is greater than that of

$N{F}_{3}$ .

In case of

$N{F}_{3}$ , fluorine is more electronegative than nitrogen, so it will attract the shared pair of electron towards itself from nitrogen. As a result dipole due to all

$F$ is in opposite direction to the resultant dipole due to

$N-F$ bonds, therefore the net dipole decreases.

$N{H}_{3}$ , Nitrogen is more electronegative than

$H$ , so it will attract the shared pair of electrons towards itself. As a result dipole due to Nitrogen is in same direction as the resultant dipole moment due to

$N-H$ bond and hence the net dipole increases.

Hence, the net dipole moment of

$N{F}_{3}$ is less than that of

$N{H}_{3}$ .

A diatomic molecule has a dipole moment equal to 1.2 D. If the bond length is 1 ${ A }^{ 0 }$ , what fraction of electronic charge $'e'$ exists on each atom.

Electronic charge

$=$

$\dfrac{Dipole-moment}{Bond-length}$

$=\dfrac{1.2\times10^{-18}}{1\times 10^{-8}}$

$=1.2\times10^{-10} esu$

Thus, fraction of elctronic charge on each end

$=\dfrac{1.2\times 10^{-10}}{4.8\times 10^{-10}}=0.25$

$=25$ % of

$e$

Number of molecules having non-zero dipole moment.
$BeCl_{2},XeF_{2}, NH_{3},PCl_{3}F_{2},PCl_{2}F_{3},BCl_{3},SF_{6}, XeF_{4}$

Dipole moment is a vector quantity. Hence if can be broken down into a vertical and horizontal component.

The numbe of molecules having non-zero dipole moment is -

${ NH }_{ 3 }$ -The dipole moment of

${ NH }_{ 3 }$ is

$\mu =1.46 D$

${ PCl }_{ 2 }{ F }_{ 3 }$ ,

${ CH }_{ 2 }{ Cl }_{ 2 }$ - The dipole moment of

${ CH }_{ 2 }{ Cl }_{ 2 }$ is

$\mu =1.59 D$ and 1,4-dichloro-2,3-dimethyl benzene

$({ C }_{ 8 }{ H }_{ 8 }{ Cl }_{ 2 })$

The H-OH bond angle in water isThe dipole distance being $0.94{ A }^{ 0 }$ . The dipole moment for molecule is 1.85 debye. Calculate the charge on oxygen atom.
[ $\cos { { 105 }^{ 0 } }$ = 0.259(approx)].

Dipole moment

$=$ distance

$\times$ charge.

$1.85=0.94\times$ charge

charge

$=\dfrac { 1.85 }{ 0.94 } =1.96$

charge on oxygen atom

$=2$ .

Explain the terms
(i) bonding molecular orbitals,
(ii) antibonding molecular orbitals,
(iii) non-bonding molecular orbitals.

1. The bonding orbital is used in molecular orbital theory to describe the attractive interactions between the atomic orbitals of two or more atoms in a molecule.

2. An antibonding orbital is a type of molecular orbital that weakens the bond between two atoms and helps to raise the energy of the molecule relative to the separated atoms. Such an orbital has one or more nodes in the bonding region between the nuclei.

3. A non-bonding orbital $(NBMO)$ is a molecular orbital for which the addition or removal of an electron does not change the energy of the molecule. Molecular orbitals come from the linear combination of atomic orbitals.

Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but different number of electrons in their outermost shell. It was found that elements A and G combine to form an ionic compound which can also be extracted from sea water. This compound is added in a small amount to almost all vegetable dishes during cooking. Oxides of elements A and B are basic in nature while those of E and F are acidic. The oxide of D is almost neutral. Based on the above information answer the following question.

What would be the nature of compound formed by a combination of elements B and F?

$\Rightarrow$ Number of given elements are $8$ . They are $A,B,C,D,E,F,G$ and $H$ .

$\Rightarrow$ All $8$ elements are belongs to same period because they have same number of electronic shells and have different number of electrons in the outermost shell.

$\Rightarrow$ We can see the above pattern in ${ 3 }^{ rd }$ period as it have $8$ elements.

$\Rightarrow$ Nature of compound formed by a combination of element $B$ and $F$ is ionic in nature since B is metal and F is non-metal.

$\Rightarrow$ Here $\Rightarrow$ $A=Na$ (Sodium), $B=Mg$ (Magnesium),

$C=Al$ (aluminium), $D=Si$ (Silicon),

$E=P$ (Phosphorus), $F=S$ (Sulphur),

$G=Cl$ (Chlorine), $H=Ar$ (Argon).

What type of interaction hold the molecules together in a polar molecular solid?

There are two types of forces hold the molecules or atoms in apole compound

1. Vanderwall's forces of attractions.

2. Inter molecular forces on hydrogen bonds.

Compare the dipole moment of $o-dichlorobenzene (I) ; o - xylene (II) and o - nitrophenol(III)$

$O-dichlorobenzene$

$O-xylene$

$O-nitrophenol$

(Refer to Image 1) (Refer to Image 2) (Refer to Image 3)

$III > I >II$

1214189_1106772_ans_bcde71fec8eb4f3894b9acee4d078755.png

The strength of sigma bonds formed by axial overlap of s- orp-orbitals of 2nd shell of participating atoms decreases as:

Solution:-

$p$ -orbitals afford maximum axial overlap and

$s$ -orbitals have minimum.

Thus the decreasing order of extent of overlap among

$2s$ and

$2p$ orbitals is-

$p-p > p-s > ss$ .

Why dipole moment of $PF_2Cl_3$ is zero but that of $PF_3Cl_2$ is non-zero?

The compounds

$PF_3Cl_2$ and

$PF_2Cl_3$ appear to have a basic trigonal bipyramid structure,

$F$ atoms in

$PF_2Cl_3$ assume axile positions, while in

$PF_3Cl_2.$ The structure is

$C_{2v}$ , in which there are one equatarial and two axial

$F$ atoms.

This gives rise to stronger equatarial than axial bonds.

Thus dipole moment cancles out in

$PCl_3F_2$ , whereas it is non-zero in

$PCl_2F_3$ .

1051964_1113900_ans_bccbe49b7ad4404ea971c2e6886bee5c.bmp

Explain the difference between the valence electrons and the covalency of an element.

Valency is the number of free electron/electrons in the outermost shell of an element. The greatest valency could be 4.

When the valency of an element is 4 it can neither lose nor accept 4 electrons to form an ionic bond , because it would be difficult for nucleus with six protons to hold on to ten electrons, that is four extra electrons.(take in case of carbon with valency 4).

Also it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on to just two electrons. Carbon overcomes this problem this problem by sharing its valence electrons with atoms of other elements.not just carbon but many other elements form molecule by sharing the outer shell electron in this manner such bonds which are formed by sharing of an electron pair between two atoms are known as covalent bond.

Calculate the formal charge on the all atoms present in the molecules $NH_{4}^{+}$ .

Formal charge on

$N=5-4=+1$

Formal charge on

$H=1-1=0$

1380991_1118003_ans_b8909982ba944285b09a8703441eb2a8.jpg

Discuss the shape of the following molecule using VSEPR model:
$As{ F }_{ 5 }$ and ${ PH }_{ 3 }$

$As{F}_{5}$ -

The central atom has no lone pair and there are five bond pairs. Hence, the shape is trigonal bipyramidal.

$P{H}_{3}$ -

The central atom has one lone pair and there are three bond pairs. Hence, the shape is trigonal bipyramidal.

1150357_1119944_ans_ed92af547ae843048d58e3faf2fe2b3d.jpeg

$LiF$ is ionic but $BeF_2$ is covalent.
Comment on the statement.

1120238_1121483_ans_40440231acff4f8aa153ffd054669b93.jpg

What is the nature of bond in $CaH_{2}$ ?

Nature of bond in

$CaH_2$ .

The bond in

$CaH_2$ is electrovalent in nature.

Comment on the nature of bonding formed in $BF_{3}$ .

$BF_3$ ,we have

$sp^2$ hybridisation and we get back bonding.

This is the concept of back bonding so the type of bond is

$2p\pi -2p\pi$ and bond order is

$1.33$

1053054_1123807_ans_9181d7016da245dabfc26cfe912c2f5a.PNG

Write short notes on synergic bonding.

Synergic bonding:-

Synergic bonding is also known as Pi-backbonding. It is usually used in the context of organometallic chemistry where there is a transition metal centre and good pi-acceptor ligands like

$CO$ . In such a case, there are two bonding interactions at a time. Firstly donation of electrons from the ligand to an empty orbital on the which gives the typical ligand-metal interaction. However if the metal has filled d-orbitals, a second interaction can occur where the electrons are donated from the filled d orbitals on the metal to an empty orbital of the ligand (typically a Pi antibonding orbital). Together, these two interactions make up synergic bonding.

Which hydrogen bond is stronger?
$S-H-O$ or $O-H-S$

1341955_1136747_ans_82dce16a110b42c9a20523276b56192a.jpg

Account for the following:
1) The $H-S-H$ bond angle in ${ H }_{ 2 }S$ is less than the $H-O-H$ bond angle in ${ H }_{ 2 }O$
2) Dipole moment of $C{ O },\quad B{ F }_{ 3 } , CC{ I }_{ 4 }$ are zero
3) $N{ F }_{ 3 }$ is pyramidal but $B{ F }_{ 3 }$ is triangular planar

1351453_1135084_ans_aec620e3548a4560a523bd379d834ba0.jpg

In $O_{2},O_{2} and O_{2}^{^{-2}}$ molecular species, the total number of antibonding electrons respectively are ?

1342985_1136778_ans_25fc7b7042784003bbdf33a7af132e32.jpg

Bond line Formula
C-atom $\rightarrow$ denoted by corner
H-atom $\rightarrow$ Not shown
Other atom $\rightarrow$ usual rotation.

1341947_1136127_ans_3d586a9e262445479b57a4637721e140.jpg

What is covalency?

$\bf{Hint:}$ It is the number of electrons shares or accepted by an atom to complete its octet.

$\bf{Explanation:}$

When an element shares electrons with other atoms of the same or different elements to acquire stable electronic configuration, it is called covalency.

For example: covalency of oxygen is

$2$ .

$O = 2 , 6$

Because its valence shell has six electrons and it need two electron to complete it octet.

Write a short note on hydrocarbons?

Hydrocarbon refers to a molecule whose structure includes only Hydrogen and Carbon. interestingly though hydrocarbons (Once Combined) also from bonds with other atoms i order to create organic compounds. The presence of carbon is required for a compound to be classified as in all but a few cases but the presence of hydrocarbon adds even more basis for it to be considered organic as there are few inorganic compounds that do certain carbon but not hydrogen. The presence of a hydrocarbon in an organic compound means the bond between the atoms will be particularly strong,unlike the bond in inorganic compounds and organic compounds that contain a carbon Atom, the presence of other atoms leads to hydrocarbons being classified as either pure (Only Hydrogen and Carbon) or impure (Hydrogen or carbon bound to the other atoms as well as each other).

some examples of Hydrocarbon is Methane (

$C{H_4}$ ), ethene (

${C_2}{H_4}$ ), ethane (

${C_2}{H_6}$ ), ethylene (

${C_2}{H_2}$ ) etc.

What is partial -ve & +ve

The covalent bond between two atoms with different electronegative results in unequal sharing of electrons. This unequal sharing of electrons leads to partially positive and partially negative charges on the opposite ends of the bond.

For example, as shown in the above image. Here, the oxygen atom has a partial negative charge and carbon atom has a partial positive charge.

1056247_1153052_ans_78836cfae62e45bc8cd7b30f5e572d3c.PNG

Molecular compounds are usally formed by the combination between _________.

The molecular compounds are formed by the combination of two or more non-metals by sharing their electrons to achieve an octet. The non-metals shared their electrons via covalent bonds.

Boron trifluoride $(BF_3)$ has no dipole moment $(\mu = 0D)$ . Explain how this observation confirms the geometry of $BF_3$ predicted by VSEPR theory.

The $BF_3$ molecule has a symmetrical trigonal planar geometry, like the $SO_3$ molecule.

In such a structure, the resultant moment of any two $B-F$ dipoles is equal in magnitude but opposite in direction to the moment of the third one.

So, the net dipole moment of the $BF_3$ molecule is zero, and it is non-polar.

The dipole moment of water is $6.17 \times 10^{-3} cm$ . The H-O-H bond angle is $104^0$ and 0-H bond length is 96 pm. Calculate the % ironic character.

1350756_1201939_ans_696ae3bdd9bd4c6ba3fc8b1e59e290a9.jpg

Find the formal charge of each $'O'$ in ozone.

Formal charge =valence - non bonding - bounding electrons
For 1

$6-4-\dfrac{4}{2}=0$
For 2

$6-2-\dfrac{6}{2}=6-2-3=1$
For 3

$6-6-\dfrac{2}{3}=-1$
So.
1069847_1207106_ans_c2bb60fe2e2d49dd8c1fb4c9534b328b.image%2011

A diatomic molucule has a dipole moment of 2.4 D. If the bond length is 2 $\mathring { A }$ . What fraction of electronic charge exist on one of the poles?

Electronic charge 'e'=

$\cfrac {Dipole\quad moment}{Bond\quad length}$

$\Rightarrow \cfrac {1.2\times 10^{-18}}{1.0\times 10^{-0}cm}=1.2\times 10^{-10}esu$

Thus, fraction of

$e^-$ charge on each end:-

$\Rightarrow \cfrac {1.2\times 10^{-10}}{4.8\times 10^{-10}}=0.25$

Compare the $C-N$ bond-length in the following species.

1350715_1227513_ans_9a98d7a991ed42c9afd98654f82faafa.jpg

What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur ?

The structure is given

1351110_1207170_ans_30bdad107ec640fc9985c716b7f62373.PNG

If dipole moment of is $1.5 D$ , dipole moment of is:

${u}_{1},{u}_{2},{u}_{3},{u}_{4}$ are four vectors

$=\sqrt { { \left( 1.5 \right) }^{ 2 }+{ \left( 1.5 \right) }^{ 2 } } =\sqrt { +\left( 2\times 1.5\times 1.5 \right) \cos { { 120 }^{ o } } }$

$=\sqrt { 4.5-2.25 } =\sqrt { 2.25 } =1.5D$

Can we get hydrogen and oxygen by setting up an arrangement for passing current through distilled water? Why?

Pure water is bad conductor of electricity. Inorder to conduct electricity , inorder to electrolyse water it must be acidulated or made alkaline to get hydrogen due to reduction of H+ ions at anode and oxygen at cathode due to reduction

Explain why a Sigma $(\sigma)$ - bond is stronger than a Pi $(\pi)$ - bond?

Sigma bonds are formed by head-on the overlap of atomic orbitals. Whereas pi bonds are formed in addition to sigma bonds by sideways overlapping of atomic orbitals. Since the information of a sigma bond, the orbitals are along internuclear axis this results in more effective orbital overlap as compared to when pi bonds are formed as they are perpendicular to the internuclear axis. This significant difference in orbital overlap results in sigma bond being stronger than the pi bond.
1315006_1266762_ans_5add72fc13014a018ca3bdc743788b9f.gif

1315006_1266762_ans_5add72fc13014a018ca3bdc743788b9f.gif

Explain the electronic configuration :- ${\text{n}}{{\text{s}}^{{\text{2}}\,}}\,\,{\text{n}}{{\text{p}}^{\text{3}}}$ . are more stable as compared $np^3$

In electronic configuration the half filled and completely filled orbitals has extra stability due to spin multiplicity

$\uparrow \uparrow \uparrow$

$\uparrow \downarrow \,\,\,\, \uparrow \downarrow \,\,\,\, \uparrow \downarrow$

$\Rightarrow$ because of that

$n{s^2}n{p^3}$ are more stable as a orbital is fulfilled

$n{p^3}$ is half filled

${ \uparrow \downarrow }$

$\uparrow \,\, \uparrow \,\, \uparrow$

Write the significance/applications of dipole moment.

1326071_1316957_ans_eebf8125603c425084549c3268c8f6e9.jpg

Atomicity of oxygen in ozone molecule is____________.

What do you mean by noble metals?

A noble metal is any of several metallic chemical elements that have outstanding resistance to oxidation, even at high temperatures.

The grouping is not strictly defined but usually is considered to include rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold; i.e., the metals of groups VIIB, VIII, and IB of the second and third transition series of the periodic table.

Silver and gold, which with copper are often called the coinage metals, and platinum, iridium, and palladium comprise the so-called precious metals, which are used in jewelry.

Dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.
Give reason :

The dipole moment of chlorobenzene is less than cyclohexyl chloride as in chlorobenzene because

$C-Cl$ bond is

$s{p}^{2}$ hybridised whereas in cyclohexyl chloride the

$C-Cl$ bond is

$s{p}^{3}$ hybridised.

Since

$s{p}^{2}$ more

$s$ character and more electronegative than

$s{p}^{3}$ so dipole moment of chlorobenzene is lower.

Also, in chlorobenzene resonance gives rise to the partial double bond character to the carbon-halogen bond, making it stronger by reducing the polarity of the carbon-halogen bond.

Hence dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.

(i) Discuss the significance/applications of dipole moment.
(ii) Represent diagrammatically the bond moments and the resultant dipole moment in C02, NF3
and CHCl3.

(i) Dipole moment plays very important role in understanding the nature of chemical bond. A
few applications are given below:
(a) Distinction between, polar and non-polar molecules. The measurement of dipole moment can
help us to distinguish between polar and non-polar molecules. Non-polar molecules have zero dipole
moment while polar molecules have some value of dipole moment.
(b) Degree of polarity in a molecule. Dipole moment measurement also gives an idea about the
degree of polarity specially in a diatomic molecule. The greater the dipole moment, the greater is
the polarity in such a molecule.
(c) Shape of molecules. In case of molecules containing more than two atoms, the dipole moment
not only depends upon the individual dipole moments of the bonds but also on the arrangement of
bonds.
.Thus, dipole moment is used to find the shapes of molecules.
(d) Ionic character in a molecule. Knowing the electronegativities of atoms involved in a molecule, it
is possible to predict the nature of chemical bond formed. If the difference in electronegativities of
two atoms is large, the bond will be highly polar. As an extreme case, when the electron is
completely transferred from one atom to another, an ionic bond is formed. Therefore, the ionic
bond is regarded as an extreme case of covalent bond. The greater the difference in
electronegativities of the bonded atoms, the higher is the ionic character
(e) Distinguish between cis- and trans- isomers. Dipole moment measurements help to distinguish
between cis- and trans- isomers because ds-isomer has usually higher dipole moment than trans
isomer.
(f) Distinguish between ortho, meta and para isomers. Dipole moment measurements help to
distinguish between o-, m- and p-isomers because the dipole moment of p-isomer is zero and that of
o-isomers is more than that of m-isomer.

How many $\sigma$ - and $\pi$ -bonds are present in each of the following molecules?
(a) $H C \equiv C- C H = C H- C H _ { 3 }$
(b ) $C H _ { 2 } = C = C H- C H _ { 3 }$

(a)

$H C \equiv C- C H = C H -C H _ { 3 }$

Total pi bond

$=3\pi$

Total sigma bond

$=4(C-C)+6(C-H)=10\sigma$

(b )

$C H _ { 2 } = C = C H -C H _ { 3 }$

Total pi bond

$=2\pi$

Total sigma bond

$=3(C-C)+6(C-H)=9\sigma$

What's the difference between electrovalency, covalency and valency?

1356587_1587108_ans_0097ab1d47ac4bfcb962f0711c2c7d9e.jpg

Write three - dimensional ( wedge - darked wedge line ) representation for the methyl chloride $CH_{3}Cl$ compound.

figure

1232065_1601734_ans_c464427d2f7e4e68921b4105c5ad1761.PNG

Find the number of $\sigma$ bond $\pi$ bond in $1, 3$ -butadiene.

Explanation

1,3-Butadiene - Molecule of the Month June 2015 - HTML version

Structure clearly shows that it has

$9\sigma$ bonds i.e. single bonds and

$2pi$ bonds are present in

$1,3-butadiene$

(a) Discuss the significance / applications of dipole moment.
(b) Represent diagrammatically the bond moments and the resultant dipole moment in $CO_2 , NF_3$ and $CHCl_3$

1896966_1723544_ans_94488ecb97dc438d9ba1477d32d3c6af.jpg

How many $\sigma$ molecules and how many $\pi$ bonds are present in a benzene molecule?

1547491_1724014_ans_4bcb4fc812bb491e916a24d2f14ce7e8.JPG

Draw the shape $XeF_4$ and $OSF_4$ according to VSEPR theory. Show the lone pair of electrons on the central atoms.

$XeF_4: sp^3 d^2$ hybridization.

Six electron pairs around central atom four bond pairs, two lone pairs so square planar shape.

$OSF^4: sp^3d$ hybridized

Five electron pairs around the central atom, five bond pairs so trigonal bipyramidal shape.

1576968_1724025_ans_c943aa5989394fbf895134638fe6e8a3.png

State four major physical properties that can be used to distinguish between covalent and ionic compounds. Mention the distinguishing features in each case.

Properties of covalent compounds: when the difference in electronegativities of element is lesser , colvalent bond is formed.
Due to weaker forces of attarction, they have low melting and boiling points.
They are generally soft and waxy .
they are usually insoluable in polar solvents but soluble in non-polar solvents
Properties of ionic compounds : when there is a large difference between the electronegativities of elements , then ionic bond is formed
Due to stringer forces of attraction , they have high melting and boiling points.
generally they are hard and brittle.
as they are polar molecules , so are easily soluble in polar solvents.

The total number of lone-pairs of electrons in melamine is .............

$C_3N_3(NH_2)_3$
The total number of lone pairs in melamine is 6.

1547487_1724006_ans_b3ce7b87b2324d7ea9b00727f047b928.JPG

The formal charge on the carbon atom in the carbonate ion is:

1728232_1727098_ans_19540b57e4bf44a7ad640686c562281c.jpg

What types of bonds and how many of each are present in $NH_4^+ ?$

1717029_1727399_ans_f73354be4a2449788dd19b4bc38f353d.jpg

Which one of the following has strongest bond?
HF, HCl , HBr, HI

1561660_1727235_ans_baf6a0527bbf46dbb21fab24c58f6949.jpg

How many total bonds (sigma and pi bonds) are present in ozone molecule?

1560199_1727103_ans_566c150451bc487b9e9c01ecc6cb5dbd.jpg

The number of lone pairs on Xe in $XeF_6$ is:

1560220_1727131_ans_0ce6b85ce88e42859b87f179537bb386.jpg

What type of bonds are present in the following molecules?
(i) $MgF_2$ (ii) BrCI (iii) $CBr_4$ (iv) $C_2N_2$ (v) CuS (vi) $H_2O$ (vii) $H_2SO_4$ (viii) $SO_2$ (ix) $HNO_3$ (x) $K_4 Fe (CN)_6$

$(i) ionic\ (ii) Covalent\ (iii) Covalent\ (iv) Covalent\ (v) ionic\\ (vi) Covalent\ (vii) Covalent\ and\ coordinate\ (viii) Covalent\ and\ coordinate\\ (ix)\ Covalent\ and\ coordinate\ (x)\ Electrovalent\ and\ coordinate\\ (xi)\ true\ covalent\ bond\ (xii)\ semipolar\ bond\ (xiii)\ Electrovalent$

In the molecule $ICl_3$ how many lone pairs of electrons are associated with iodine ?

$ICl_3$ iodine shows sp3 d hybridization.

Lewis structure is first structure and has two extra lone pairs on the central atom.

VSEPR 3 bp + 2 lp = 5 shape is trigonal bipyramidal

So there are two lone pairs associated with iodine.

1549829_1728308_ans_830f7529388243d2b9e45b63ec29bf8d.PNG

How many lone pairs are present in nitrogen molecule?

Correct answer: 2

Reason:- Molecular formula of Nitrogen molecule is N2. The nitrogen atoms are bonded with triple bonds. So, each of them have a lone pair of electron. Hence, total number of lone pair is 2

How many $\sigma$ - bonds are present in $N_2O_3$ ?

1625393_1729520_ans_9c605c4cb703482cbba40762cb9c61de.jpg

How many lone pairs of electrons are present on Xenon atom in $XeF_4$ ?

It has 2 lone pair of electrons .

1657949_1729042_ans_4e009c276be142bb87783ea849def1f4.png

The ratio of lone pairs and the number of $S-S$ bonds in $S_8$ molecules is:

$S_8$ molecule has the following structure. Each sulphur atom is in

$sp^3$ hybridized state.

Number of lone pairs

$=2\times8=16$

Number of

$S−S$ bonds

$=8$

Ratio

$=\dfrac{16}{8}=2$

1575177_1734266_ans_625b73bda3ac4b878ae0074a4e18b5b5.jpg

How many sigma bonds are present in $Cr_2O_7^{2-}$ ion?

1722255_1732058_ans_49d5ba9b093746faa8e0e35f3b7e74b5.jpg

The difference in the number of $\sigma$ and $\pi$ bonds in trimer of $SO_{3}\ i.e \ S_{3}O _{9}$ (consider no coordinate bond to be present )

$σ = 3 + 9 = 12$

$,π \ bond = 6$

Thus, The difference in the number of

$σ$ and

$π$ bonds in trimer of

$SO_3$ is

$12-6=6$

1865126_1746529_ans_0a5726d9473b4c389d56beda5cdbe2f6.png

How many lone pairs are present in $OF_{2}$ molecule?

1686318_1730032_ans_e147e0df5d4a4f76a420afb8c0b98875.jpg

Number of ${ sp }^{ 2 }-{ sp }^{ 2 }$ sigma bonds in given compound $A$ is:

1612340_1750403_ans_d0a82610eac849c5b2d230defaa837ae.png

Explain the following statement:
Some alkali metals can be cut with a knife.

Some alkali can be cut with a knife because they are very soft and low densities.

Arrange the followint compounds in increasing order of diple moment:
${ CH }_{ 3 }{CH}_{2}{ CH }_{ 3 },{ CH }_{ 3 }{ CH }_{ 2 }{NH}_{2},{ CH }_{ 3 }{ CH }_{ 2 }OH$

Since oxygen is more electronegative than nitrogen, $CH_3CH_2OH$ has greater dipole moment than $CH_3CH_2NH_2$ .
Propane is non polar molecule. Hence it has the least dipole moment.

Hence the order is:

${ CH }_{ 3 }{CH}_{2}{ CH }_{ 3 }< { CH }_{ 3 }{CH}_{2}{NH}_{2}< { CH }_{ 3 }{CH}_{2}OH$

Define Chemical bond.

$Chemical$

$bond$ is the binding force between two or more atoms of a molecule.

What do you understand by lone pair and shared pair?

A pair of electrons which is not shared by any other atoms is called lone pair of electrons.
The electrons of valence shell shared by two atoms to form covalent bond are called shared pair of electrons.

Define :
a chemical bond

A chemical bond may be defined as the force of attraction between any two atoms in a molecule to attain stability.

Match the pairs.

A) Photosynthesis is a chemical change (3).

B) Water consist of covalent bonds (4).

C) Sodium chloride contains ionic bond (5).

D) Dissolution of salt in water is a physical change (6).

E) Carbon is a reactant in combustion process (2).

F) Fluorine, highly electronegative element has tendency to form anions (7).

G) Magnesium has a tendency to loose elctrons (1).

Define a Chemical bond.

$chemical$

$bond$ is a force which holds the atoms of a molecule in a compound

What do you understand by a chemical bond?

A chemical bond is an

$\textbf{attractive force}$ that holds the atoms of a molecule together, in a compound.

In $XeF_2\ ,XeF_4,\ and\ XeF_6$ , the number of lone pairs on $Xe$ , is ________.

$XeF_2 ,XeF_4,$ and

$XeF_6$ , the number of lone pairs on Xe, is

$3,2,1$ respectively
1781906_1821451_ans_405de1cb285744a9a514581dc0cf690b.PNG

Calculate the value of X-Y, for $XeOF_{4}$ . (X = Number of $\sigma$ bond pair and Y = Number of lone pair on central atom)

$X=5,Y=1$

$X-Y=5-1=4$

1781932_1821458_ans_195d8d75a0194881a169d476bcea6551.png

Calculate x + y + z for $H_{3}PO_{3}$ acid, where x is no. of lone pairs , y is no. of bonds and z is no.of $\pi$ bonds

In the given molecule the number of lone pairs (x) is 6, number of sigma bonds (y), and number of π bonds (z) are 6 and 1 respectively. Hence

$x+y+z=13.$
1780000_1821462_ans_7862aa0a3b7743c89020118fb427de92.png

What is dipole moment ?

Dipole Moment is the product of the distances of charge (positive or negative) centers and the distance between the center.

What is covalency ?

Covalency is the number of electrons shared between the atoms during covalent bond formation.

How many sigma bonds are present in ethane ?

There are 7

$\sigma$ (6C-H bonds and 1 C-C bond) bonds in ethane.

What is chemical bonding ?

Chemical bonding is the attractive force that holds or binds constituents were atoms, ions or molecules together in a substance.

Draw the electron-dot structure of $S_8$ molecule.

Electron-dot structure of

$S_8$ molecule is shown above.
1734534_1823414_ans_c3075310e4314d05ac981acce65717e6.png

What is a sigma bond ?

Sigma bond is a bond formed by the overlapping of atomic orbital along the axis.

What do you mean by lone pair of electron ?

The pair of electron which involves in hybridization but not involves in covalent bond formation (involves in co-ordinate bond formation) is called as lone pair.

Give the scientific reason for the following:

In the atmosphere, oxygen is available as $O_2$ but not as O.

Valency of oxygen is

$2$ because it can accept or share

$2$ electrons to form a bond. Hence it is available as

$O_2$ but not as O.

Calculate the value of "x + y - z" here x,y and z are total number of non-bonded electron pair(s), pie bond(s) and sigma bonds in hydrogen phosphite ion respectively .

$x = 7,y = 1, z = 5,$

$x + y - z = 7 + 1 - 5 = 3$
1801861_1821467_ans_a7da3a03b1674f0485957f7e540b26ca.png

How are atoms in these compounds held together?

Atoms in the compounds formed by these elements are held together by strong electrostatic attractive force.

Which one of the following has the highest dipole moment?
$CCl_4$

$CCl_4$ is a symmetrical molecule. Therefore, the dipole moments of all four

$C-Cl$ bonds cancel each other. Hence its resultant dipole moment is zero.
As shown in the above figure, in

$CHCl_3$ , the resultant dipole moments of two

$C-Cl$ is opposed by the resultant dipole moments of one

$C-H$ an don e

$C-Cl$ bond. Since the resultant of one

$C-H$ and one

$C-Cl$ bond is smaller than the resultant than the resultant of the two

$C-Cl$ bonds dipole moments, the opposition is to a small extent. As a resultant

$CHCl_3$ has a small net dipole moment.
On the other hand in case of

$CH_2Cl_2$ the resultant dipole moments of two

$C-Cl$ bonds is strengthened by the resultant of the dipole moments of two

$C-H$ bonds. As a result,

$CH_2Cl_2$ has a higher dipole moment. Hence

$CH_2Cl_2$ has the highest dipole moments among the three compounds.
Hence the given compounds can be arranged in the increasing order of their dipole momens as

$CCl_4 < CHCl_3 < CH_2Cl_2$
1751981_1828483_ans_556afba4c4af4180af5d7afc60e2ee22.png

Define dipole moment.

Dipole moment is the product of electric charge and distance between the positive and negative species present in the molecule.

Perform the experiments arranging the apparatus as shown in the figure.
Record your observations and identify what type of compounds sodium chloride and sugar are.

When electricity is passed through sodium chloride solution in which carbon rod is immersed, hydrogen and chlorine gas are produced. It is an ionic compound.

In the second, when electricity is passed through sugar solution there is no charge because of which it does not conduct electricity. Hence it belongs to covalent compound.

What is meant by Chemical Bonding?

The attractive force that holds the atoms together in the formation of a molecule is called chemical bonding.

The electronic configuration of magnesium and chlorine are $2 , 8 , 2$ and $2 , 8 , 7$ respectively. How many electrons does a magnesium atom donate ? What charge will it get ?

$2$ , two positive

$(2+)$

In the formation of sodium chloride which atoms are combined?

In the formation of sodium chloride sodium and chlorine atoms are combined.

Which of the following molecule / molecules will have zero dipole moment ?
$CO_{2}, H_{2}O, CCl_{4}, CHCl_{3}, BF_{3}, BeF_{2}, NH_{3}.$

$CO_{2}, CCl_{4}, BF_{3}$ and

$BeF_{2}.$

Complete the equation of this process
$Cl+ 1e^- \rightarrow$

$Cl + 1e^- \rightarrow Cl^{-}$

Mention the chemical bond in following molecules or compounds:
Sodium fluoride

Sodium fluoride - In sodium fluoride compound, two sodium and fluoride ions are held together by ionic bond.

Taking x-axis as the internuclear axis, which out of the following will form $\sigma$ -bond ?
(i) 1s and 1s (ii) 1s and 2 $p_x$ (iii) 2 $p_y$ and 2 $p_y$ (iv) 1s and 2s.

All except (iii).

What is chemical bond? Explain its types giving one example of each.

Chemical bond is a bond by which the atoms in the molecule of a compound are combined and held together by a strong combining force. There are two types of chemical bonds; ionic bond and covalent bond.

1. Ionic Bond: Ionic bond is the bond formed by a strong force of attraction between two oppositely charged ions.

Example - In sodium chloride

$(NaCl)$ , ionic bond is present between the two elements; sodium and chlorine which form sodium ion and chloride ion respectively.

2. Covalent Bond: The bond formed between two combining atoms by sharing of electrons of the outermost orbit to achieve octet configuration is called a covalent bond.

Example - In oxygen molecule, the two atoms of oxygen achieve octet configuration by sharing two-two electrons from each of the oxygen atoms and form two covalent bonds between oxygen atoms.

Let us complete the equation for this process,
$Mg \rightarrow Mg^{2+} +$ .................

$Mg \rightarrow Mg^{2+} + 2e^-$

Mention the chemical bond in following molecules or compounds:
Potassium bromide

Potassium bromide - In potassium bromide compound, two potassium and bromide ions are held together by ionic bond.

What is the valency of a molecule?

The number of electrons gained, lost or shared in the bonding of one atom with another is called the valency of that atom.

Fill in the blanks:
The atom which loses electrons acquires a ............... charge.

The atom which loses electrons acquires a positive charge.

What are the SI units of dipole moment ?

Coulomb meter (Cm).

Compound $A [C_{4}H_{8}N_{2}]$ on hydrolysis in acidic medium gave $B$ ( $[C_{4}H_{9}O_{2}N]$ ). A on reduction with $LiAlH_{4}$ gave $C$ $([C_{4} H_{12} N_{2}])$ .'B' on treatment with $NaHCO_{3}$ solution liberates $CO_{2}$ . 'B' on heating forms $D$ ( $[C_{4}H_{7}ON]$ ). 'D' on reduction with $LiAlH_{4}$ forms secondary amine $E$ ( $[C_{4}H_{9}N]$ ). Number of single bonds in final compound E are:

The number of $P-O-P$ bonds in tricyclic metaphosphoric acid is:

From figure it can be seen that, it have 3

$P-O-P$ bonds .

Match the species in List-I with the number of lone pairs given in List-II.

$Xe{ F }_{ 2 }$ :Total valence electrons (TVE)

$=8+2$

$=10$

$5$ pairs in total

$2$ bp and hence

$3$ lp

$\Rightarrow Xe{ F }_{ 2 }$

electrons -16 e(8\times 2)=6 e\rightarrow \quad 3\quad lone\quad pairs$$

$Xe{ F }_{ 4 }=8+7(4)=36e-32e(8\times 4)=4e\rightarrow 2\quad lone\quad pairs$

$Xe{ F }_{ 6 }=8+7(6)=50e-48e(8\times 6)=2e\rightarrow 1\quad lone\quad pair$

${ Sf }_{ 6 }=6+7(6)=48e-48e(8\times 6)=0e\rightarrow No\quad lone\quad pairs$

$Ca (OCl)_2$ .

From the diagram, we can say the given compound has 2 covalent bonds in the molecule.

Match the list of type of bonds (List I) with list of compounds (List II).

Ionic- CaCl₂

Single covalent- H₂O, NH₃, CH₄

Coordinate covalent- NH₄⁺

Hydrogen bond- H₂O, NH₃

Multiple covalent- C₂H₂

Match type of bond (given in List I) with method of formation (given in List II).

$\sigma$ undergoes axial overlapping,
Covalent bond is formed by sharing electrons,
Ionic bond is formed by transfer of electrons,

$\pi$ undergoes lateral overlapping.

By the following method you can predict the geometrical shape of species with only one central atom, without first drawing the Lewis structure :
Total number of electron pairs = (number of valence electrons $\pm$ electrons (for ionic) charge)/2
Number of bond electron pairs = number of atoms - 1
Number of electron pairs around central atom = total number of electron pairs - 3 [number terminal atoms (except H)]
Number lone pair = (number of central electron pairs - number of bond pairs)

How many of the following have trigonal bipyramidal shape based on this method?
$(a) PCl_5\, \, \, (b) NH_3\, \, \, (c) H_2O$ $(d) {ClO_3}^- \, \, \, (e) {ICl_4}^-$

	Step
Species	1	2(x)	3	4(E)	VSEPR notation	Structure
(a) $PCl_5$	$\displaystyle \frac{5 + (5 \times 7)}{2}=20$	5	$20-15=5$	$5-5 = 0$	$AX_5$	trigonal bipyramidal
(b) $NH_3$	$\displaystyle\frac{5 + 3}{2}=4$	3	$4-0=4$	$4-3=1$	$AX_3E$	trigonal pyramidal
(c) $H_2O$	$\displaystyle\frac{2+ 6}{2}=4$	2	$4-0=4$	$4-2=2$	$AX_2E_2$	angular
(d) $ClO_3^-$	$\displaystyle\frac{7+18+ 1}{2}=13$	3	$13-9=4$	$4-3=1$	$AX_3E$	Pyramidal
(e) $ICl_4^-$	$\displaystyle\frac{7+28+ 1}{2}=18$	4	$18-12=6$	$6-4=2$	$AX_4E_2$	Square planar

All the structures determined by this new method is similar to that used by VSEPR theory and is widely acceptable.

Considering $x-$ axis as the internuclear axis, the overlap of which of the following orbitals will not form a sigma bond and why?
(a) $1s$ and $2s$
(b) $1s$ and $\displaystyle 2 p_{x}$
(c) $\displaystyle 2p_{y}$ and $\displaystyle 2p_{y}$
(d) $1s$ and $2s$

The combination

$c$ will not result in the formation of sigma bond as it will result in sideways overlap.
This will result in the formation of

$\pi$ bond. In the options

$a, b$ and

$d$ , sigma bond will be formed.

The following table shows the electronic configuration of the elements $W, X, Y, Z$ :
Element W X Y Z
Electronic configuration 2, 8, 1 2, 8, 7 2, 5 1
Answer the following questions based on the table above :
(i) What type of Bond is formed between :
$W$ and $X$ $Y$ and $Z$
(ii) What is the formula of the compound formed between :
$X$ and $Z$ $W$ and $X$

(i)

1. W has 1 electron extra whereas X needs 1 electron in order to attain the stable electronic configuration of its nearest inert gas. Hence, W will donate and X will accept electron resulting in an ionic bond.

2. Z has only 1 electron hence it needs 1 electron to attain the stable electronic configuration of its nearest inert gas whereas Y also needs 1 electron. Hence, both Y and Z will share their 1 electron with each other forming a covalent bond.

(ii)

1. The valency of X is -1 whereas that of Z is +1. Hence, ZX compound will be formed.

2. The valency of W is -1 whereas that of X is +1. Hence, XW compound will be formed.

How many $\sigma$ and $\pi$ bonds are presents in each of the following molecule?
(a) $HC \equiv C -CH =CH - CH_3$ (b) $CH_2 = C = CH - CH_3$

(a)

$H-C\equiv C-CH=CH-CH_{3}$

$\sigma$ bond is a stronger bond than the

$\pi$ bond.

No. of sigma bond

$=4(C-C)+6(C-H)=10$

No.of pi bond

$=3$

(b)

$CH_{2}=C=CH-CH_{3}$

No. of sigma bonds

$=3(C-C)+6(C-H)=9$

No. of pi bonds

$=2$

Calculate formal charge of atoms $HClO_{4}, C{{O}_{3}}^{2}$ .

The formal charge on three oxygen atom has electron pair shared by chlorine,

$Cl=\dfrac { v-1 }{ 2S-L } =0=\dfrac { 6-1 }{ 2\times 2-6 } =-1$

The formal charge on the oxygen atom having an electron pair shared by chlorine and hydrogen, then the formal charge is :

$0=\dfrac { 1-1 }{ 2\times 2-0 } =0$

Formal charge on

$H$ is

$0=\dfrac { 1-1 }{ 2\times 2-0 } =0$

For the

${ Co }_{ 3 }^{ 2 }$

For the oxygen:

$6-4-\dfrac { 1 }{ 2 } \times 4=0$

For the carbon atom:

$4-0-\dfrac { 1 }{ 2 } \times 8=0$

For the second oxygen:

$6-6-\dfrac { 1 }{ 2 } \times 2=-1$

In the formation of compound between two atoms $A$ and $B$ , $A$ looses two electrons and $B$ gain one electron.
(a) What is the nature of bond between $A$ and $B$ ?
(b) Explain the formation of $MgCl_2$ molecule.
(c) Common salt conducts electricity only in the molten state. Why?
(d) Why is melting point of $NaCl$ high?

(a) Since the bond formation involves loss and gain of electrons, the bond formed must be ionic.

(b) Formation of

$MgCl_{2}$ molecule:

$Mg\rightarrow Mg^{2+}+2e^{-}$

$2Cl+2e^{-}\rightarrow 2Cl^{-}$

$\therefore Mg^{2+}+2Cl^{-}\rightarrow MgCl_{2}$

$NaCl$ is melted, the ions become mobile. Due to this they can conduct electricity.

(d) Due to strong electrostatic interactions between the ions

$Na^{+}$ &

$Cl^{-}$ , more energy is required to break this interaction. Hence, due to this it has high melting point.

Dipole moment of $H_2S$ is $0.95$ D. Calculate the bond moment if the bond angle is $97^0$ .
$(cos \ 48.5^0 = 0.662)$

$\mu =2$ ( S-H bond moment )

$\times \cos \left( \dfrac{\theta}{2}\right)$

$\Rightarrow 0.95=2$ ( S-H bond moment )

$\times \cos$

$\Rightarrow 0.95=2$ ( S-H bond moment )

$\times 0.663$

$\Rightarrow S-H$ bond moment

$=\dfrac{0.95}{1.326}=0.716 \simeq 0.72.$

Hence, the answer is

$0.72.$

1205552_1115049_ans_70bf0b097faf41b3a99f1116e2a0381d.png

Based on $MO$ theory compare the relative stabilities of $O_{2}$ & $O_{2}^{2-}$ and indicate their magnetic properties.

Bond order is directly proportional to stability.
Magnetic nature depends paired and unpaired electrons.
If molecule has unpaired electrons it means molecule is paramagnetic nature.
And if the molecule has no unpaired electron{ e.g., all are paired electrons } then, a molecule is diamagnetic nature.
Electronic configuration of

$O_{ 2 }$ (16 electrons):

$σ1s²,σ*1s², σ2s²,σ*2s², (π2px²≈π2Py²),(π*2Px¹≈π*2Py¹)$

Na(Anti bonding molecular orbitals) = 6 , Nb(Bonding molecular orbitals) = 10

Bond order=

$\dfrac { 1 }{ 2 }$ [bonding molecular orbotals - anti bonding

molecular orbotals]

now, B.O =

$\dfrac { 1 }{ 2 } [ 10 - 6] = 2$

It has two unpaired electrons.so,

$O_{ 2 }$ molecule is paramagnetic.

Electronic configuration of

${ O }_{ 2 }^{ 2- }$ (17 electrons):

$σ1s²,σ*1s², σ2s²,σ*2s², (π2px²≈π2Py²),(π*2Px²≈π*2Py²)$

now, B.O =

$\dfrac { 1 }{ 2 } [10 -8] = 1$

It has no unpaired electron.so, it is diamagnetic

Now, the bond order is directly proportional to stability so, higher the bond order will be a higher stable molecule or ion.
Hence, increasing order of stability is

$O_{ 2 }>{ O }_{ 2 }^{ 2- }$

Arrange- $NH_3;BF_3$ and $NF_3$ in the increasing order of their Dipole moment, giving reasons.

1343076_1134469_ans_bbe7583477594e5f9acd55fea729e75b.jpg

Write down correct order of covalent character of the following.
a . LiCl , NaCl , RbCl , KCl
b. NaCl , Mg $Cl_2$ , Si $Cl_4$
c . Sn $Cl_2$ , Sn $Cl4$

In an ionic compound, the ability of cation to attract the electrons of anion is called the polarizing power. Due to polarizability of anion, it gets distorted & sharing of electrons take place and ionic compounds possess some covalent character.

Greater is the polarization , greater is the covalent character.

$\therefore$ Decreasing order of covalent character is

(1)

$LiCl>NaCl>KCl>RbCl$

Since smaller the cation , more is the covalent character.

(2)

$SiCl_{4}>MgCl_{2}>NaCl$

Since cation has more positive charge & is more covalent.

(3)

$SnCl_{4}>SnCl_{2}$

Since oxidation state of

$Sn$ is

$+4$ &

$+2$ i.e. more positive charge, more covalent.

Write chemical equation for the following reaction.
Reaction of ethanolic $NH_3$ with $C_2H_5Cl$ .

1187294_1266618_ans_80016300a01c4138ae1e8b05d6fb5ce6.png

How many of the following substance have higher lattice energy than $NaBr$ ?
$CaCI_{2}, NaI, CsBr, LiF, MgO, AI_{2}O_{3}, TiO_{2}, KI_{3}$

1336763_1318089_ans_0bb13575bc054e82a333e4ee96cbf1b4.jpg

How many sigma (T) bond present in $CH_2=C=CH-CH_3$

1338163_1309661_ans_a36d56551d5f404c965e8c11eba4b745.jpg

How many $3C - 4e^-$ bonds are present in dimer of $BeCl_2$ ?

2038777_1722964_ans_56255352cee748c5b5095e3ba01b29a0.jpg

Find the ratio of the total number of bonds to the total number of lone pairs in $C_3N_3Cl_3 .$

Total number of bonds= 9

$\sigma$ bonds + 3

$\pi$ bonds= 12

Total lone pair = 12

$\dfrac{12}{12}=1$

1547013_1723554_ans_c7d7989325d94f829be8e01706485edc.png

Find the ratio between $\sigma$ - bond and $\pi$ - bond in $C_3N_3Cl_3$ .

There are total 9

$\sigma$ bonds and 3

$\pi$ bonds

Ratio=

$\dfrac{9}{3}=3$

1546985_1723520_ans_5c9ed3fae58c489e98f657631aa767b8.png

Find the ratio of $\sigma$ -bonds to $\pi$ -bonds in $P_5O_{16} ^{7-}$ .

Structure of

$P_{5}O_{16}^{7-}$ is shown above

therefore , we can say

Number of

$\sigma$ bond = 20

Number of

$\pi$ bond = 5

$\therefore$ ratio of

$\sigma$ bond to

$\pi$ bond =

$\frac{20}{5}$ = 4

Hence , the answer is 4.

Explain the following with relevant reason.
The $B-X$ distance is shorter than what is expected theoretically in ${BX}_{3}$ molecule $(X=Cl, F, Br, I)$ ?

The bond

$B-X$ in

${BX}_{3}$ has double bond character due to back bonding. This brings resonance in the molecule which is responsible for shorter

$B-X$ distance than expected.
1617588_1729923_ans_fbd0b1c6798a437f87d94d3a1f8e410c.jpg

Dipole moment of certain diatomic molecule X-Y is 0.38 D. If the X-Y distance is 158 pm, the percentage of electronic charge developed on X-atom is:

1729664_1727121_ans_f312b86f6e65401fbff4abdb61178660.jpg

A diatomic molecule has a dipole moment of $1.2$ D. If its bond distance is $1.0\overset{o}{A}$ , what fraction of an electronic charge, e, exists on each atom? ( $1 D=10^{-18}$ esu cm and $e=4.8\times 10^{-20}$ esu).

1611413_1740174_ans_a52db98686c34994a3de9472076fa6cd.jpg

Account for the following:
The bond angle in ${NH_4}^+$ is higher than $NH_3$ .

$NH_3\Rightarrow$ Hybridisation =

$Sp^3$

structures

$\Rightarrow$ Refer image,

here, the single lone pair causey lone pair bond pair repulsion, for this steric effect, the bp-bp repulsion decreases and the hydrogen atoms come closer to each other. So the molecule loses the identical bond angle

$(109^028')$ and the bond angle becomes

$107^0$ .

$NH_4^+\Rightarrow$ Hybridisation =

$Sp^3$

structure, Refer image,

here, the single lone pair is involved in bonding with a more hydrogen atom and hence, the structure is a perfect tetrahedral.

2040392_1777999_ans_cfa1e449ae3642eab2144650d3f99155.png

An oxyacid of phosphorus is triprotic in nature. Identify the compound and draw its electron dot formula.

An oxyacid of phosphorus which is triprotic in nature is phosphoric acid

$(H_3PO_4)$ because there are three acidic hydrogen present in the compound.

(

$H_3PO_4$ - Electron dot structure)

1712069_1812400_ans_654c753b9d49422ea31483317c9941b7.png

Taking the $HOH$ bond angle in $H_{2}O$ molecule as $105^\circ,$ calculate the charge on oxygen atom. Given that the dipole moment of $H_{2}O$ molecule is $1.84\,D$ and $O-H$ bond distance is $0.94 \,\mathring {A}.$

$\mu_{H_2O} = \sqrt{ \mu^2_{OH} + \mu^2_{OH} + 2\mu^2_{OH} \,cos \,105^\circ}$

$\therefore (1.84)^{2} = 2\mu^2_{OH} + 2\mu^2_{OH} \times (0.2588)$

$3.3856 = 2 \mu^2_{OH} (1 - 0.2588)$

$[cos \,105^\circ = cos (180 - 75^\circ) = -cos \,75^\circ]$

$= 1.4824 \,\mu^2_{OH}$
or

$\mu^{2}_{OH} = 2.2839$
or

$\mu_{OH} = 1.51\,D = 1.51 \times 10^{-18} esu \,cm.$
But

$\mu_{O - H} = Charge (\delta) \times d$

$\therefore 1.51 \times 10^{-18} esu \,cm = \delta \times (0.94 \times 10^{-8} cm)$
or

$\delta = 1.606 \times 10^{-10} \,esu.$
As

$O$ atom acquires charge

$= 2\delta$ (One

$\delta$ from each

$O - H$ bond ) therefore charge on

$O$ -atom)

$= 2 \times 1.606 \times 10^{-10} esu$

$= 3.212 \times 10^{-10} esu$

Chemical Bonding And Molecular Structure - Class 11 Medical Chemistry - Extra Questions

The structure of a peptide is given below.If the absolute values of the net charge of the peptide at pH=2,pH=6pH = 2, pH = 6 and pH=11pH = 11 are |z1|,|z2|,|z_1|, |z_2|, and |z3||z_3|, respectively, then what is |z1|+|z2|+|z3|?|z_1|+|z_2| + |z_3| ?

What is meant by the term chemical bond and chemical bonding?

The covalency of sulphur in the sulphur molecule (S8S_8) is :

Total number of the sigma bonds present in benzene ring are:

__________ overlapping between orbitals leads to π\pi bond formation.

11 mole of Na2S2O3Na_2 S_2 O_3 looses 1010 moles of e−e^{-} . Determine final Oxidation number of S.

Isotopes are the atoms of same element, with same atomic number. But with different __________.

Define isotopes.

What are co-ordinate bonds?

What is a lone pair of electrons?

A certain mass of a gas occupies a volume of 2 L at STP. To what temperature the gas must be heated to double its volume, keeping the pressure constant?

How many lone pair of electrons are present on the central atom of CH4,H2O,NH3,PCl3CH_4, H_2O, NH_3, PCl_3 and PCl5PCl_5 molecules?

What types of overlapping take place in a sigma and a pi bond?

Total number of lone pair of electrons on XeXe in XeOF4XeOF_{4} is ________.

By using an expanded octet for the sulphur atom in thionyl chloride (SOCl2_{2}), you can write a Lewis structure with no formal charge.If true enter 1 else 0

If true enter 1, else enter 0.When ethene reacts with H2H_2, ethane is formed. The π \pi bond of C=C is affected. Thus, π \pi bond is more reactive than σ \sigma -bond.

Consider the following Lewis Dot structure:[:¨N=N=¨N:]−\left[: \ddot{N} = N = \ddot{N}:\right]^-The formal charge on the central NN atom is:

How many σ\sigma bonds are present in the Lewis structure of HONOHONO?

Consider the following Lewis Dot structure:[:¨O=N=¨O:]+\left[: \ddot{O} = N = \ddot{O}:\right]^+The sum of formal charges on NN and OO is:

How many σ\sigma bonds are present in the Lewis structure of H2N−OHH_2N-OH ?

How many σ\sigma bonds are present in H2N−NO2H_2N-NO_2?

Formal charge on sulphur in SO2SO_2 is:

Out of CH2Cl2,CH4,CCl4,H2O,CHCl3,d−CH_2Cl_2, CH_4, CCl_4, H_2O, CHCl_3, d-dichlorobenzene, oo-cresol, pp-xylene, SCl2,BF3,IBrSCl_2, BF_3, IBr and CH2OCH_2O, non zero value of dipole moment are:

Numbers of geometric isomers of PBr2Cl3PBr_2Cl_3 molecule which have non-zero dipole moment are:

Ratio of bond pair-lone pair electrons XeOF2XeO{F}_{2} is:

Maximum number of atoms which can be attached on NN-atom are :

If true enter 1, else enter 0.Hydrogen bond is weaker than a covalent bond.

If the statement is true enter 1, else enter 0. Repulsion between bond pair-bond pair electron is lesser than in between lone pair-lone pair.

Number of Sugden's singlet bonds in PCl5P{Cl}_{5} is :

If true enter 1, else enter 0.The HH-bond energy is around 8.4kJ8.4kJ mol−1{mol}^{-1}.

Number of unpaired electrons in O2[AsF4]{O}_{2}[As{F}_{4}] is :

In acetylene, there are ______ (two/four) π\pi - bonding electrons between carbon atoms.

The dipole moment of CH3OH{CH}_{3}OH ____ (more/less) than that of CH3SH{CH}_{3}SH

The number of lone pairs of an electron on central iodine atom of I−3{I}_{3}^{-} ion is:

Find the number of lone pairs of electrons on XeXe in XeOF4.XeOF_4.

Find the ratio of the total number of bonds to the total number of lone pairs in C3N3Cl3C_3N_3Cl_3.

Find the ratio of lone pairs to π\pi bond (present in ring).in C3N3(NH2)3C_3N_3\, (NH_2)_3.

Draw the electron dot structure of Ethanoic acid

Explain the nature of the covalent bond using the bond formation in CH3Cl C{ H }_{ 3 }Cl

In NO3−{NO_3}^- ion, find the sum of bond pairs and lone pairs of electrons on nitrogen atom.

1.

Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms in C2H4 \displaystyle C_{2}H_{4} and C2H2 \displaystyle C_{2}H_{2} molecules.

What do you understand by bond pairs and lone pairs of electrons? Illustrate by giving one example of each type.

Find the number of lone pairs and bond pairs in SF6{SF}_{6}.

Linear molecules possess _______ dipole moment.

Lone pairs and bond pairs possess electrons. However, the repulsion experienced by lone pairs is much greater than that experienced by bond pairs. What reason can be attributed to this?

In the formation of water molecule, _________ number of lone pairs and ________ number of bonds pairs are present.

The number of bond pairs in the molecule PCl5PCl_5 is __________.

Why do only valence electrons involve in bond formation? Why not electron of inner shells? Explain.

Explain the formation of sodium chloride and calcium oxide on the basis of the concept of electron transfer from one atom to another atom.

What is a Chemical bond?

Why water drops (dew) form on flowers and grass during morning hours of winter season ?

A, B, and C are three elements with atomic number 6, 11, and 17 respectively. Which of these can form an ionic bond as well as covalent bonds?

Oxidation number of Cr in K3CrO8{ K }_{ 3 }{ CrO }_{ 8 } is (1) +6+6 (2) +5+5(3) +3+3 (4) +2+2

Calculate the fractional charge value of HCl the dipole moment is 1.021.02D.

Which of the following molecules posses more dipole moment and why?NH3{ NH }_{ 3 } or NF3{ NF }_{ 3 }

What is the total number of sigma bonds and pi bonds in the following molecules?C2H3ClC_2H_3Cl, CH2Cl2CH_2Cl_2, H3C−H|C=H|C−C≡C−HH_3C-\overset{H}{\overset{|}{C}}=\overset{H}{\overset{|}{C}}-C\equiv C-H

Number of σ\sigma bonds and π\pi bonds in methyl cyanide are xx and yy respectively. Value of x+yx+y

Explain the formation of a chemical bond.

Give reasons:(i) BF3{BF}_{3} has zero dipole moment although the B−FB-F bonds are polar.(ii) NaClNaCl is harder than NaNa metal.

How many bond pair and lone pair are there in CO2−3CO_3^{2-}?

What is the dipole moment of BeF2BeF_2 molecule? Account for your answer.

What is the differnece between σ\sigma and π\pi bonds?

Compare and justify the dipole moment of NH3{ NH }_{ 3 } and NF3.{ NF }_{ 3 }.

A diatomic molecule has a dipole moment equal to 1.2 D. If the bond length is 1 A0{ A }^{ 0 }, what fraction of electronic charge ′e′'e' exists on each atom.

Number of molecules having non-zero dipole moment.BeCl2,XeF2,NH3,PCl3F2,PCl2F3,BCl3,SF6,XeF4BeCl_{2},XeF_{2}, NH_{3},PCl_{3}F_{2},PCl_{2}F_{3},BCl_{3},SF_{6}, XeF_{4}

The H-OH bond angle in water isThe dipole distance being 0.94A00.94{ A }^{ 0 }. The dipole moment for molecule is 1.85 debye. Calculate the charge on oxygen atom.[cos1050\cos { { 105 }^{ 0 } } = 0.259(approx)].

Explain the terms (i) bonding molecular orbitals, (ii) antibonding molecular orbitals, (iii) non-bonding molecular orbitals.

What type of interaction hold the molecules together in a polar molecular solid?

Compare the dipole moment of o−dichlorobenzene(I);o−xylene(II)ando−nitrophenol(III)o-dichlorobenzene (I) ; o - xylene (II) and o - nitrophenol(III)

The strength of sigma bonds formed by axial overlap of s- orp-orbitals of 2nd shell of participating atoms decreases as:

Why dipole moment of PF2Cl3PF_2Cl_3 is zero but that of PF3Cl2PF_3Cl_2 is non-zero?

Explain the difference between the valence electrons and the covalency of an element.

Calculate the formal charge on the all atoms present in the molecules NH+4NH_{4}^{+}.

Discuss the shape of the following molecule using VSEPR model: AsF5As{ F }_{ 5 } and PH3{ PH }_{ 3 }

LiFLiF is ionic but BeF2BeF_2 is covalent. Comment on the statement.

What is the nature of bond in CaH2CaH_{2}?

Comment on the nature of bonding formed in BF3BF_{3}.

Write short notes on synergic bonding.

The structure of a peptide is given below.
If the absolute values of the net charge of the peptide at $pH = 2, pH = 6$ and $pH = 11$ are $|z_1|, |z_2|,$ and $|z_3|$ , respectively, then what is $|z_1|+|z_2| + |z_3| ?$

The covalency of sulphur in the sulphur molecule ( $S_8$ ) is :

__________ overlapping between orbitals leads to $\pi$ bond formation.

$1$ mole of $Na_2 S_2 O_3$ looses $10$ moles of $e^{-}$ . Determine final Oxidation number of S.

How many lone pair of electrons are present on the central atom of $CH_4, H_2O, NH_3, PCl_3$ and $PCl_5$ molecules?

Total number of lone pair of electrons on $Xe$ in $XeOF_{4}$ is ________.

By using an expanded octet for the sulphur atom in thionyl chloride (SOCl $_{2}$ ), you can write a Lewis structure with no formal charge.
If true enter 1 else 0

If true enter 1, else enter 0.
When ethene reacts with $H_2$ , ethane is formed. The $\pi$ bond of C=C is affected. Thus, $\pi$ bond is more reactive than $\sigma$ -bond.

Consider the following Lewis Dot structure:

$\left[: \ddot{N} = N = \ddot{N}:\right]^-$

The formal charge on the central $N$ atom is:

$HONO$ ?

Consider the following Lewis Dot structure:

$\left[: \ddot{O} = N = \ddot{O}:\right]^+$

The sum of formal charges on $N$ and $O$ is:

$H_2N-OH$ ?

How many $\sigma$ bonds are present in $H_2N-NO_2$ ?

Formal charge on sulphur in $SO_2$ is:

Out of $CH_2Cl_2, CH_4, CCl_4, H_2O, CHCl_3, d-$ dichlorobenzene, $o$ -cresol, $p$ -xylene, $SCl_2, BF_3, IBr$ and $CH_2O$ , non zero value of dipole moment are:

Numbers of geometric isomers of $PBr_2Cl_3$ molecule which have non-zero dipole moment are:

Ratio of bond pair-lone pair electrons $XeO{F}_{2}$ is:

Maximum number of atoms which can be attached on $N$ -atom are :

If true enter 1, else enter 0.
Hydrogen bond is weaker than a covalent bond.

If the statement is true enter 1, else enter 0.

Repulsion between bond pair-bond pair electron is lesser than in between lone pair-lone pair.

Number of Sugden's singlet bonds in $P{Cl}_{5}$ is :

If true enter 1, else enter 0.
The $H$ -bond energy is around $8.4kJ$ ${mol}^{-1}$ .

Number of unpaired electrons in ${O}_{2}[As{F}_{4}]$ is :

In acetylene, there are ______ (two/four) $\pi$ - bonding electrons between carbon atoms.

The dipole moment of ${CH}_{3}OH$ ____ (more/less) than that of ${CH}_{3}SH$

The number of lone pairs of an electron on central iodine atom of ${I}_{3}^{-}$ ion is:

Find the number of lone pairs of electrons on $Xe$ in $XeOF_4.$

Find the ratio of the total number of bonds to the total number of lone pairs in $C_3N_3Cl_3$ .

Find the ratio of lone pairs to $\pi$ bond (present in ring).in $C_3N_3\, (NH_2)_3$ .

Explain the nature of the covalent bond using the bond formation in $C{ H }_{ 3 }Cl$

In ${NO_3}^-$ ion, find the sum of bond pairs and lone pairs of electrons on nitrogen atom.

Draw diagrams showing the formation of a double bond and a triple bond between carbon atoms in $\displaystyle C_{2}H_{4}$ and $\displaystyle C_{2}H_{2}$ molecules.

Find the number of lone pairs and bond pairs in ${SF}_{6}$ .

In the formation of water molecule, _ number of lone pairs and number of bonds pairs are present.

The number of bond pairs in the molecule $PCl_5$ is __________.

Oxidation number of Cr in ${ K }_{ 3 }{ CrO }_{ 8 }$ is
(1) $+6$ (2) $+5$
(3) $+3$ (4) $+2$

Calculate the fractional charge value of HCl the dipole moment is $1.02$ D.

Which of the following molecules posses more dipole moment and why?
${ NH }_{ 3 }$ or ${ NF }_{ 3 }$

What is the total number of sigma bonds and pi bonds in the following molecules?
$C_2H_3Cl$ , $CH_2Cl_2$ , $H_3C-\overset{H}{\overset{|}{C}}=\overset{H}{\overset{|}{C}}-C\equiv C-H$

Number of $\sigma$ bonds and $\pi$ bonds in methyl cyanide are $x$ and $y$ respectively. Value of $x+y$

Give reasons:
(i) ${BF}_{3}$ has zero dipole moment although the $B-F$ bonds are polar.
(ii) $NaCl$ is harder than $Na$ metal.

How many bond pair and lone pair are there in $CO_3^{2-}$ ?

What is the dipole moment of $BeF_2$ molecule? Account for your answer.

What is the differnece between $\sigma$ and $\pi$ bonds?

Compare and justify the dipole moment of ${ NH }_{ 3 }$ and ${ NF }_{ 3 }.$

A diatomic molecule has a dipole moment equal to 1.2 D. If the bond length is 1 ${ A }^{ 0 }$ , what fraction of electronic charge $'e'$ exists on each atom.

Number of molecules having non-zero dipole moment.
$BeCl_{2},XeF_{2}, NH_{3},PCl_{3}F_{2},PCl_{2}F_{3},BCl_{3},SF_{6}, XeF_{4}$

The H-OH bond angle in water isThe dipole distance being $0.94{ A }^{ 0 }$ . The dipole moment for molecule is 1.85 debye. Calculate the charge on oxygen atom.
[ $\cos { { 105 }^{ 0 } }$ = 0.259(approx)].

Explain the terms
(i) bonding molecular orbitals,
(ii) antibonding molecular orbitals,
(iii) non-bonding molecular orbitals.

Compare the dipole moment of $o-dichlorobenzene (I) ; o - xylene (II) and o - nitrophenol(III)$

Why dipole moment of $PF_2Cl_3$ is zero but that of $PF_3Cl_2$ is non-zero?

Calculate the formal charge on the all atoms present in the molecules $NH_{4}^{+}$ .

Discuss the shape of the following molecule using VSEPR model:
$As{ F }_{ 5 }$ and ${ PH }_{ 3 }$

$LiF$ is ionic but $BeF_2$ is covalent.
Comment on the statement.

What is the nature of bond in $CaH_{2}$ ?

Comment on the nature of bonding formed in $BF_{3}$ .

Which hydrogen bond is stronger?
$S-H-O$ or $O-H-S$

Account for the following:
1) The $H-S-H$ bond angle in ${ H }_{ 2 }S$ is less than the $H-O-H$ bond angle in ${ H }_{ 2 }O$
2) Dipole moment of $C{ O },\quad B{ F }_{ 3 } , CC{ I }_{ 4 }$ are zero
3) $N{ F }_{ 3 }$ is pyramidal but $B{ F }_{ 3 }$ is triangular planar

In $O_{2},O_{2} and O_{2}^{^{-2}}$ molecular species, the total number of antibonding electrons respectively are ?

Bond line Formula
C-atom $\rightarrow$ denoted by corner
H-atom $\rightarrow$ Not shown
Other atom $\rightarrow$ usual rotation.

Boron trifluoride $(BF_3)$ has no dipole moment $(\mu = 0D)$ . Explain how this observation confirms the geometry of $BF_3$ predicted by VSEPR theory.

The dipole moment of water is $6.17 \times 10^{-3} cm$ . The H-O-H bond angle is $104^0$ and 0-H bond length is 96 pm. Calculate the % ironic character.

Find the formal charge of each $'O'$ in ozone.

A diatomic molucule has a dipole moment of 2.4 D. If the bond length is 2 $\mathring { A }$ . What fraction of electronic charge exist on one of the poles?

Compare the $C-N$ bond-length in the following species.

If dipole moment of is $1.5 D$ , dipole moment of is:

Explain why a Sigma $(\sigma)$ - bond is stronger than a Pi $(\pi)$ - bond?

Explain the electronic configuration :- ${\text{n}}{{\text{s}}^{{\text{2}}\,}}\,\,{\text{n}}{{\text{p}}^{\text{3}}}$ . are more stable as compared $np^3$

Dipole moment of chlorobenzene is lower than that of cyclohexyl chloride.
Give reason :

(i) Discuss the significance/applications of dipole moment.
(ii) Represent diagrammatically the bond moments and the resultant dipole moment in C02, NF3
and CHCl3.

How many $\sigma$ - and $\pi$ -bonds are present in each of the following molecules?
(a) $H C \equiv C- C H = C H- C H _ { 3 }$
(b ) $C H _ { 2 } = C = C H- C H _ { 3 }$

Write three - dimensional ( wedge - darked wedge line ) representation for the methyl chloride $CH_{3}Cl$ compound.

Find the number of $\sigma$ bond $\pi$ bond in $1, 3$ -butadiene.

(a) Discuss the significance / applications of dipole moment.
(b) Represent diagrammatically the bond moments and the resultant dipole moment in $CO_2 , NF_3$ and $CHCl_3$

How many $\sigma$ molecules and how many $\pi$ bonds are present in a benzene molecule?

Draw the shape $XeF_4$ and $OSF_4$ according to VSEPR theory. Show the lone pair of electrons on the central atoms.

What types of bonds and how many of each are present in $NH_4^+ ?$

Which one of the following has strongest bond?
HF, HCl , HBr, HI

The number of lone pairs on Xe in $XeF_6$ is:

What type of bonds are present in the following molecules?
(i) $MgF_2$ (ii) BrCI (iii) $CBr_4$ (iv) $C_2N_2$ (v) CuS (vi) $H_2O$ (vii) $H_2SO_4$ (viii) $SO_2$ (ix) $HNO_3$ (x) $K_4 Fe (CN)_6$