Nitrogen Family/Gp-15 Pnicogens - PowerPoint Presentation

Slide1

Nitrogen Family/Gp-15

Pnicogens

/Inertness

Slide2

Group Members

N(7)

[He]2

s

2

2p

3

Non-Metal

P(15)-

[Ne]3

s

2

3p

3

Non-Metal

As(33)-

[

Ar

]3

d

10

4s

2

4p

3

Metalloid

Sb

-(51)

[Kr]4

d

10

5s

2

5p

3

Metalloid

Bi-(83)

[

Xe

]4

f

14

5d

10

6s

2

6p

3

Non Metal

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Electron afinity

:-

Amount of energy released when one electron is accepted by the atom. The electron afinity goes on decreasing down the group.

Electronegativity

:-

The tendency of an element to attract a bonded pair of electron towards itself.

15

th

group elements are more electronegative than 14

th

group because they are smaller in size.

Electronegativity goes on decreasing down the group.

Slide5

Metallic character

:-

Metallic character goes on increasing down the group.

Non-metallic character

:-

It goes on decreasing down the group.NITROGEN & PHOSPHOROUS are non-metals.ARSENIC & ANTIMONY are metalloids. BISMITH is a metal.

Slide6

Oxidation state

:-

Common oxidation state shown by these are +3 & +5 , but as we go down the group the +3 state is predominant due to inert pair effect.

Inert pair effect

:-

The lower oxidation state is preferred over higher oxidation state as we go down the group. This is due to reluctant of

S electrons to contribute in the bond formation due to poor shielding effect of d orbitals.

Slide7

NITROGEN

shows a wide range of

oxidation state since it is a non metal.

OS MOLECULE

-3

 NH

3 -2  NH2 NH2 -1  NH2OH

0  N2

1  N

2

O

2  NO

3  HNO

2

4  NO

2

5  HNO

3

Slide8

CHEMICAL PROPERTIES

Hydrides

Halides

Oxides

Oxo-acids

Disproportanation reactionHydrides :-they are as follows NH3  Ammonia

PH3 

Phosphine

AsH

3

 Arsine

SbH

3

 Stibine

BiH

3

 Bismuthine

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BASIC NATURE OF HYDRIDES;

These hydrides are lewis bases.

Ammonia is most basic in nature because the lone pair of electron is localized due to smaller size .

As the size increases the lone pair of electron get scaterred and are not available.

NH3>PH3>AsH3>SbH3>BiH3 BOND ANGLE; The bond angle decreases down the group. NH3>PH3>AsH3>SbH3>BiH3107° 93° 92 ° 91° 90°

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REDUCING PROPERTY

Substance capable of giving

H

easily is called as reducing agent.

NH3<PH3<AsH3<SbH3<BiH3

BiH3 is very good reducing agent b’cause t is Bond length between Bi-H is longer.

Slide13

DISPROPORTANATION REACTION;

when reactant of one oxidation state can give product of two or more than two oxidation state.

3HNO

2

 HNO3+2NO+H2O ( In acidic medium) 4H3PO

33H

3

PO

4

+PH

3

Slide14

HALIDES OF GROUP -15

N

-forms NCL

3

,NF

3. It is pyramidal in shape & has sp3 hybridization.

Slide15

Ncl

5

does not exit b’cause no vacant no d orbital.

Pcl3 is pyramidal with sp3 hybridisation.

P=3s

2

3p3

Slide16

Pcl

5

is triangular pyramidal with sp3 hybridization

Slide17

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Group-15 oxides;

nitrogen forms a large variety of oxides ;

N

2

O(NITROUS)

PREPARATION: NH4NO3N2O+2H2ONO(NITRIC OXIDE)

PREPARATION:

2FeSo

4

+2NaNo

2

+3H

2

So

4

Fe

2

(So4)

3

+2NaHSo

4

+2H

2

O+2NO

Slide19

N

2

O

3

(DINITROGEN TRIOXIDE)

2NO+N

2O42N2O3 NO2(NITROGEN DIOXIDE) 2Pb(NO3

)24NO

2

+2PbO

2

N

2

O

4

(DINITROGEN TETRAOXIDE)

2NO

2



N

2

O

4

Slide20

PREPARATION METHODS (lab):-

Ammonium chloride & sodium nitrite when heated gives nitrogen.

NH

4

Cl + NaNO

2

 N2 + NaCl + 2H2OAmmonium dichromate undergoes decomposition to give nitrogen (NH

4)

2

Cr

2

O

7

 N

2

+ Cr

2

O

3

+ 4H

2

O

Slide21

PHYSICAL PROPERTIES

:-

NITROGEN is colorless, odorless, tasteless & very inactive. This is because it is less reactive due to high bond dissociation energy.

CHEMICAL PROPERTIES

:-With metals it forms Nitrides 6Li +N2  2Li3N 6Na + N2

 2Na3

N

With non-metals

N

2

+ H

2

 2NH

3

N

2

+

O

2



2NO

Slide22

USES OF NITROGEN

:-

It is used in refrigerants.

Manufacturing of ammonia.

Nitrogen is used to fill up electric bulbs.

Ammonia:- NH3. It is sp3 hybridized It is pyramidal in shape , good lewis base because it has lone pair of electron.

Slide23

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Ammonia lab preparation

:-

Ammonium chloride when treated with sodium hydroxide forms ammonia.

NH

4

Cl + NaOH  NH3 + NaCl +H2O Ammonia can also be prepared from urea . NH2CONH

2 + 2H2

O  (NH

4

)2CO

3

 2NH

3

+ CO

2

+ H

2

O

Ammonia can also be prepared by treating ammonium sulphate with calcium hydroxide.

(NH

4

)

2

SO

4

+ Ca(OH)

2

 CaSO

4

+ 2NH

3

+ 2H

2

O

Slide25

USES OF AMMONIA

:-

Ammonia is used for preparing fertilizers.

& for preparing Nitric acid .

NITRIC ACID :- N  +5 State HNO3 is a oxo-acid or oxyacid . HNO3 has a plannar structure. It is a monoprotic acid , it releases only 1 H+ ions.

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GROUP 15

QUESTION &ANSWER

Slide28

Q1)WRITE THE STATE OF HYBRIDISATION OF

N

IN NO

2

?

ANS)

SP2 HYBRIDISATION.Q2) IN TRIMETHYLAMINE, ‘N’ IS PYRAMIDAL, IN N(SiH3)

3, IT IS PLANAR, WHY?

ANS) IT IS DUE TO

SP

3

HYBRIDISATION AND ONE LONE PAIR IN N(CH

3

)

3

WHEREAS IN SiH

3

, THERE IS

SP

2

HYBRIDISATION,

LONE PAIR OF ELECTRTONE IS DONATED TO VACANT D-ORBITAL

OF ‘

Si’

WHEREAS ‘C’

DOESN’T HAVE D-ORBITAL.

Slide29

Q3)WHAT IS HYBRIDISATION OF ‘’ IN SF

6

&’P’ IN PCl

5

? GIVE THERE SHAPE

ANS) ‘S’ IN SF

6 IN SP3D2 HYBRIDISED & OCTAHEDRAL SHAPED ‘P’ IN PCl5

IS SP

3

d

HYBRIDISED AND

TRIGONAL BIPYRAMIDAL

S

F

F

F

F

F

F

p

Cl

Cl

Cl

Cl

Cl

Slide30

Q4) WHY IS NITROGEN GAS WHEREAS PHOPHORUS SOLID?

ANS) N

2

MOLECULES HAVE LESS VAN DER WALLS’ FORCE OF ATTRACTION WHEREAS P4 MOLECULES HAVE MORE VAR DER WALLS’ FORCE OF ATTRACTION.

Q5) MENTION THE CONDITION REQUIRED TO MAX. YIED OF NH3?

ANS) [1] MODERATE TEMP. = 700K

[2] HIGH PRESSURE = 20MPa [3] IRON OXIDE + AL2O3 + K20 AS CATALYST

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Q6) WHY DO NITROGEN SHOW ANOMALOUS BEHAVIOUR?

ANS) IT IS DUE TO

{1} SMALLEST ATOMIC SIZE

{2} HIGHEST ELECTRONAGTIVITY

{3}

No d-ORBITALS

Q7) HOW DOES NH3 REACT WITH A SOLUTION OF Cu2+ ?ANS)

Cu2+ (

aq) + 4NH

3

(aq) [

Cu(NH

3

)

4

]

2

+

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Q8) WHY DOES NCl5 NOT EXIT?

ANS) IT IS BECAUSE ‘N’ DOES NOT HAVE D- ORBITALS.

Q9) WHY DOES NH

3

ACT AS LEWIS BASE?

ANS)IT IS DUE TO PREESNCE OF LONE PAIR OF ELECTRONS ON N.

Q10) WHY BiH3, THE STRONGEST REDUCING AGENT ALL THE HYDRIDES OF GROUP 15?ANS) IT IS BECAUSE IT HAS LOWEST BOND DISSOCIATION ENERGY DUE TO LONGEST BOND LENGTH.

Slide33

Q11) DISCUSS THE PATTERN OF VARIATION IN THE OXIDATION STATE OF THE FOLLOWING: P TO Bi?

ANS) THE TENDENCY TO SHOW -3 OXIDATION STATE DECREASES DOWN THE GROUP DUE TO DECREASE IN ELECTRONEGTIVITY. THE TENDENCY TO SHOW +5 OXIDATION STATE DECREASE FROM P TO Bi WHEREAS TENDENCY TO SHOW +3 OXIDATION STATE INCREASES DUE TO INERT PAIR EFFECT.

Slide34

Q12) THROUGH NITROGEN EXHIBITES +5 OXIDATION STATE,IT DOESN’T FROM PENTAHALIDE. GIVE REASON.

ANS) IT SHOW +5 OXIDATION STATE IN N2O5 INVOLVING ONE COORDINATE BOND. N WITH n=2,HAS s AND p ORBITALS ONLY. IT DOESN’T HAVE

d-ORBITALS

TO EXPAND ITS VALENCE SHELL. THAT IS WHY IT DOESN’T FORM PENTAHALIDE.

Slide35

Q13)

PH

3

HAS LOWER B.P THAN

NH

3. WHY?ANS) UNLIKE NH3,PH3 MOLECULES AREN’T ASSOCIATED THROUGH HYDROGEN BONDING IN LIQUID STATE. THAT IS WHY THE B.P. OF PH3 IS LOWER THAN NH3.Q14) WHY IS N

2 LESS REACTIVE AT ROOM TEMP. THAN P

4

?

ANS) BECAUSE OF STRONG P-P OVERLAP RESULTING INTO THE TRIPLE BOND,

N=N

HAVING HIGH BOND DISSOCIATION ENERGY.

P

4

HAS SINGLE BOND, LOW DISSOCIATION ENERGY

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Thank You

Amit

Sharma

PGT Chemistry