Nauman Ahmed

8/19/2019 Nauman Ahmed

1/58

NAUMAN AHMAD

Lecturer Chemistry


2/58

SOLID STATE

CHEMISTRY


3/58

contents

• Introduction• Types of solids• Crystal Structures

• Elements of Symmetry• Bragg’s equation• Allotropes of carbon: Diamond, grapite !

"ullerene


4/58

INTRODUCTION

Tree pases of matter: #as

$iquid Solid


5/58

#asmolecules

5


6/58

$iquid

molecules

6


7/58

Solidmolecules

7


8/58

What is solid?

• Definite sape%• Definite &olume%• 'igly incompressible%

• (igid%• Constituent particles eld closely by strong

intermolecular forces%

• "i)ed position of constituents%


9/58

TYPES OF SOLIDS

T*o types +based upon atomic arrangement, binding energy, pysical ! cemical properties:

-% Crystalline.% Amorpous


10/58

C!stalline solids

• Te building constituents arrange temsel&es in regularmanner trougout te entire tree dimensional net*or/%

• E)istence of crystalline lattice%• A crystalline lattice is a solid figure *ic as a definite

geometrical sape, *it flat faces and sarp edges%• Incompressible orderly arranged units%• Definite sarp melting point%•

Anisotropy%• Definite geometry%• #i&e )0ray diffraction bands%• E)amples: 1aCl, CsCl, etc%


11/58

AMORPHOUS SOLIDS

• Deri&ed from #ree/ *ord 23morpe’ meaningsapeless%

• 1o regular but apa4ard arrangement of atoms ormolecules%

• Also considered as non0crystalline solids or super0cooled liquids%• 1o sarp m%p%• Isotropic%• 1o definite geometrical sape%• Do not gi&e )0ray diffraction bands%• E)amples: glass, rubber, plastics%


12/58

T!"es o# c!stal st$ct$es

• Ionic crystals• Co&alent crystals• 5olecular crystals

• 5etallic crystals


13/58

Ionic c!stals• $attice points are occupied by positi&e and negati&e ions%

• 'ard and brittle solids%• 'ig m%p% due to &ery strong electrostatic forces of

attraction%• 6oor conductors of electricity in solid state but good in

molten state%• 6ac/ing of speres depends upon:

presence of carged species present%

difference in te si4e of anions and cations%• T*o types: AB types% AB. types%


14/58

Co%alent c!stals

• $attice points are occupied by neutral atoms%• Atoms are eld togeter by co&alent bonds• 'ard solids%

• 'ig m%p%• 6oor conductors of electricity%• T*o common e)amples: diamond ! grapite%


15/58

Molec$la c!stals

• $attice points are occupied by neutral molecules%• Te molecules are eld togeter by &ander

7aal’s forces%

• 8ery soft solids%• $o* m%p%• 6oor conductors of electricity%


16/58

Metallic c!stals

•

$attice points are occupied by positi&e metal ionssurrounded by a sea of mobile e0% • Soft to &ery ard%• 5etals a&e ig tensile strengt%

• #ood conductors of electricity%• 5alleable and ductile%• Bonding electrons in metals remain delocali4ed o&er

te entire crystal%• 'ig density%


17/58

La&s o# s!''et!

• 6lane of symmetry•

Centre of symmetry• A)is of symmetry%


18/58

Ele'ents o# s!''et!in c$(ic c!stal

• (ectangular planes of symmetry: 9• Diagonal planes of symmetry: •

A)es of four0fold symmetry: 9• A)es of tree0fold symmetry: ;• A)es of t*o0fold symmetry:

• Centre of symmetry: - Total symmetry elements: 23


19/58

Planes o# s!''et!

(ectangular plane ofsymmetry: 9 Diagonal plane ofsymmetry:


20/58

A)is o# s!''et!

"our0fold a)is ofsymmetry: 9 Tree0fold a)is ofsymmetry: ;


21/58

A)is * cente o# s!''et!

T*o0fold a)is ofsymmetry: Centre of symmetry: -


22/58

T!"es o# c$(ic c!stals

"our types:-% Simple or primiti&e type.% Body0centered

9% "ace0centered;% End face0centered


23/58

Simple or primiti&e type +sc Body0centered cell +bcc


24/58

"ace0centered cell +fcc End face0centered cell


25/58

N$'(e o# ato's "e $nit cellin a c$(ic lattice

• Simple cubic cell: -atom


26/58

Simple cube

No of atoms per unit cell= 8 x 1/8=


27/58

No of atoms per unit cell= 8 x 1/8 =


28/58

Simple cubic arrangement

e.g.Polonium52% of the space is occupied by the atoms


29/58

Body centered cubic lattice

No of atoms present per unit cell

= (8 x 1/8 ) + (1 x


30/58

No of atoms per unit cell= (8 x 1/8) +1= 2


31/58

Body centered cubic lattice

e.g. CsCl, CsBr

68% of the space is occupied by the atoms

" d bi l i


32/58

"ace0centered cubic lattice

No of atoms present per unit cell

= (8 x 1/8 ) + (6 x


33/58

"ace0centered cubic lattice

e.g. NaCl, NaF, KBr, MgO

74% of the space is occupied by the atoms


34/58

End face0centered cubic lattice

# ato's "esent "e $nit cell

+ - ) . - 1 2 ) . 2 +


35/58

Ato'ic adi$s o# a c$(ic lattice

• Simple cubic cell:r = a


36/58

Radi$s atio $le

• (elation bet*een te radius, co0ordinationnumber and te structural arrangement of temolecule%

(adius ratio =

• #reater te radius ratio, larger te si4e of te

cation and ence te co0ordination number%

E l # di3 t t l


37/58

E)a'"les o# di3eent c!stals!ste's

S.No. System Example

-% Cubic 1aCl, Cl, Ca"., Cu, nS, CsCl, Cu.3

.% 3rtorombic BaS3;, 139, 5gSi39, .S3;, CdS3;,AgBr

9% Tetragonal Sn3., Ti3., rSi3; ;% 5onoclinic CaS3;%.'.3, monoclinic S

% Triclinic CuS3;%'.3, 1a'S3;, '9639

% 'e)agonal 6bI., 5g, Cd, n, n3, B1, Si3., 'gS,CdS

% (omboedral or Trigonal #rapite, ICl, Al.39, calcite +CaC39, As,Sb, Bi

C bi l tti


38/58

Cubic lattice

O th h bi l tti


39/58

Orthorhombic lattice

T t l l tti


40/58

Tetragonal lattices

li i l tti


41/58

onoclinic lattice

T i li i l tti


42/58

Triclinic lattice

!e agonal lattice


43/58

!exagonal lattice

"hombohe#ral $Trigonal% lattice


44/58

"hombohe#ral $Trigonal% lattice

St$ct$es o# i'"otant ionic


45/58

St$ct$es o# i'"otant ionicco'"o$nds

-% AB type: 1aCl +roc/ salt CsCl nS +4inc blende < spalerite

.% AB. type: Ca". +fluorite

Ti3. +rutile

Si3.

# l , 4


46/58

• "CC type%

• Co0ordination number :%

• Calculation o& no. o& atoms o&

NaCl'unitcell:Cl at corners: +? × -


47/58

St$ct$e o# sodi$' choide

uic unit cell!mallest repeatale unit

Structure o& CsCl


48/58

Structure o& CsCl

• bcc type%

• Co0ordination number ?:?%• 1umber of atoms


49/58

Structure o& (nS •

fcc type%• Co0ordination number

;:;%• Calculation o& no. o&atoms'unit cell:

Total S = ?)-


50/58

Structure o& Ca)2

• fcc type%• Co0ordination number: ?:;

+? for cation, ; for anion

G1ote: All te compounds of AB. type follo* te same pattern%

"#

Ca+

Structure o& * O


51/58

Structure o& * 2O

• fcc type%• Co0ordination number: ;:?

; for cation ? for anion

Na+

$ #2


52/58

St$ct$e o# i'"otantco%alent co'"o$nds

-% Diamond.% #rapite

%iamon&


53/58

%iamon&

'tructure of &iamon&


54/58

'tructure of &iamon&• fcc type%•

Tetraedral• C0C bond lengt = -%9;A• (efracti&e inde) = .%;

• 'ig dispersi&e po*er of ligt• 1on0conductor of electricity• 9d net*or/

• 'ardest substance e&er /no*n%• sed as abrasi&e%

3#+ structure o& #iamon#


55/58

3#+ structure o& #iamon#

raphite


56/58

raphite


57/58

Structure o& raphite

•

3ne of te softest substances e&er /no*n%• .0d e)agonal layer structure• C0C bond lengt = -%;A• Inter layer distance = 9%;A• Sliding nature• sp. ybridisation *it one electron left o&er%• Specific gra&ity .%.• Electrical conductor • 5etallic lustre• sed as good lubricant%

2#+ structure o& graphite


58/58

2#+ structure o& graphite

Nauman Ahmed

Documents

Transcript of Nauman Ahmed