Structures of Solids

SOLIDS

can be divided into two two catagories.  catagories.  Crystalline  Amorphous

Crystalline has long range order  Amorphous materials have short range order  Effect of Crystallinity on Physical properties properties  - ex. Polyethylene 1

7PE* 0" C/7*A,,!%E *0,!'* Crystal ype

Particles

!nterparticle "orces

Physical #ehaviour

Examples

Atomic

Atoms

'ispersion

roup A  %e to /n

$olecular 

$olecules

'ispersion 'ipole-dipole (-bonds

$etallic

Atoms

$etallic bond

!onic

Positive and !on-ion negative attraction ions

) *oft ) +ery low mp ) Poor thermal and electrical conductors  "airly soft  ,ow to moderate mp   Poor thermal and electrical conductors  *oft to hard  ,ow to very high mp  $ellable and ductile  Excellent thermal and electrica electricall conductors  (ard and brittle  (igh mp   ood thermal and electrical conductors in molten condition ) +ery hard ) +ery high mp ) Poor thermal and electrical conductors

 %etwor& 

Atoms

Covalent

02 P (20 *ucrose

 %a Cu "e

 %aCl Ca"2 $g0

*i0234uart56 C 3'iamond6 2

7PE* 0" C/7*A,,!%E *0,!'* Crystal ype

Particles

!nterparticle "orces

Physical #ehaviour

Examples

Atomic

Atoms

'ispersion

roup A  %e to /n

$olecular 

$olecules

'ispersion 'ipole-dipole (-bonds

$etallic

Atoms

$etallic bond

!onic

Positive and !on-ion negative attraction ions

) *oft ) +ery low mp ) Poor thermal and electrical conductors  "airly soft  ,ow to moderate mp   Poor thermal and electrical conductors  *oft to hard  ,ow to very high mp  $ellable and ductile  Excellent thermal and electrica electricall conductors  (ard and brittle  (igh mp   ood thermal and electrical conductors in molten condition ) +ery hard ) +ery high mp ) Poor thermal and electrical conductors

 %etwor& 

Atoms

Covalent

02 P (20 *ucrose

 %a Cu "e

 %aCl Ca"2 $g0

*i0234uart56 C 3'iamond6 2

STRUCTURES OF CRYSTALLINE SOLID TYES

Na+ Cl-

Molecular Solids

Covalent Solids

Ionic solids

Metallic solids 8

'!A$0%'

49A/:

/AP(!E



CRYSTAL CRYST AL STRUCTURE STRUCTUR E Cr!stal structure  is

the "eriodic arran#e$ent o% ato$s  in the crystal. Association of each lattice "oint  with a group of atoms3#asis atoms 3#asis or $otif6. $otif6. Lattice< !nfinite array of points in space in which each point has identical surroundings to all others. S"ace Lattice ≠ Arrangement  Arrangementss of atoms = ,attice of points onto which the atoms are hung.

) ) )

) ) )

) ) )

+

*pace ,attice +  #asis

* *

Crystal *tructure

Elemental solids 3Argon6< &asis = sin#le ato$' Polyatomic Elements< &asis = t(o or %our ato$s. ; Complex organic compounds< &asis t)ousands o% ato$s

ONE DIMENTIONAL LATTICE

a

ONE DIMENTIONAL UNIT CELL UNIT CELL < &uildin# loc, re"eats in a re#ular (a!

a

a

>

T.O DIMENTIONAL LATTICE

?

T.O DIMENTIONAL UNIT CELL TYES

 b a a a ≠ b θ = @B

a ≠ b θ ≠ @B a  b a ≠ b θ = @B

 b

a = b θ =12B

a = b θ = @B a a

a a



E/AMLE OF T.O DIMENTIONAL UNIT CELL

@

T.O DIMENTIONAL UNIT CELL OSSI&ILITIES OF NaCl

Na+ Cl-

1

T0REE DIMENTIONAL UNIT CELLS 1 UNIT CELL S0AES 2

8

3

4 5

6

7 11

LATTICE TYES

Primitive 3  6

"ace Centered 3 F 6

#ody Centered 3 I 6

C-Centered 3C 6 12

&RA9AIS LATTICES

8 UNIT CELL TYES + 5 LATTICE TYES * 25 &RA9AIS LATTICES 18

COUNTIN: ATOMS IN T0E T0REE DIMENTIONAL UNIT CELL

Atoms in different positions in a cell are shared by differing numbers of unit cells  9erte; cells

 Ed#e ato$

s)ared ! 5 cells

2

 Face ato$

s)ared ! 3 cells

2

 &od! uni?ue

to 2 cell

2

1> ato$ "er cell

15 ato$ "er cell

13 ato$ "er cell

2 ato$ "er cell 1

CLOSE-AC@IN: OF S0ERES

1;

SIN:LE LAYER AC@IN:

SUARE AC@IN:

CLOSE AC@IN:

Close-pac&ing-0E/A:ONAL coordination of each sphere 1>

T.O LAYERS AC@IN:

1?

T0REE LAYERS AC@IN:

1

1@

0e;a#onal close "ac,in#

Cuic close "ac,in#

2

C9#!C C,0*E PACE'

(EFA0%A,C,0*E PACE'

+. 1 atom = 8D r 8 +. 9nit cell = a8 = r 8 Efficiency of pac&ing = +.  atom < +. unit cell = +.  atom < +. cubic = ?;

85B S"ace is occu"ied'

+. 1 atom = 8D r 8 +. 9nit cell = >.a.c = >.3r.rG86.c Eff. 0f pac&.= +. > atom < +. hexagonal = ?;

Coordination nu$er * 23 21

NON-CLOSE-AC@ED STRUCTURES

+. 1 atom = 8D r8 +. 1 atom = 8D r8 +. 9nit cell = a8 = r8 +. 9nit cell = a8 = r8 Eff. 0f pac&. = +. 2 atom < +. cubic Eff. 0f pac&. = +. 1 atom < +. cubi = >2 = ;28 7>B o% s"ace is occu"ied Coordination nu$er * >

63B o% s"ace is occu"ied Coordination nu$er * 7

22

C/7*A, 'E%*!!E* ' = mass per sel satuan  +olume sel satuan = massa molar x : molar volum = "H x :  3+ x %6 += volume sel satuan  %= bilangan avogadro := Iumlah atom dalam sel satuan ' = 3 "H x : x1>>6 + 3A6

gramcm8

28

*tructure

Nonclose "ac,in#

Close "ac,in#

Primitive Cubic #odycentered Cubic (exagonal close pac&ed Cubic close  pac&ed

Coordination number  >

*tac&ing  pattern  AAAAA…



 ABABAB…

12

 ABABAB…

12

 ABCABC…

2

ri$itive cuic &od! centered cuic Face centered cuic

Coordination nu$er

7

>

23

2;

2>

ALLOTROES

E;istence o% sa$e ele$ent in di%%erent cr!stal structures' e#' Caron

Dia$ond

:ra")ite

&uc,$inster%ullerene

2?

TYE OF 0OLES IN CLOSE AC@IN:

TETRA0EDRAL 0OLES

OCTA0EDRAL 0OLES

2

LOCATION OF OCTA0EDRAL 0OLES IN CLOSE AC@IN:

2@

LOCATION OF TETRA0EDRAL 0OLES IN CLOSE AC@IN:

8

IONIC CRYSTAL STRUCTURES

Ionic structures $a! e derived %ro$ t)e occu"ation o% )oles ! o""ositel! c)ar#ed ions

0ctahedral holes

.?82 J 1



Cubic holes 82

IONIC CRYSTAL TYES

!onic crystal type A/

A/3

Co-ordination *tructure type number  A

/

7

7

NaCl

>

>

CsCl

7

4

Rutile

5

Fluorite