States of Matter 12.pdf unit 5 physical pharmaceutics 1

unit 5 physical pharmaceutics 1

1. STATESOFMATTER
-Presentedby-
Ms.Poonam.D,Dighe
AmrutvahiniCollegeofPharmacy,Sangamner

2. Solids:Generalproperties
Solidsaremuchdenserthanbothgasesandliquidsduetothepresence
ofverystrongintermolecularforces.
Solidsareessentiallyincompressible(smallemptyspaces)
Solidshavedefinitevolumeandshape(rigid,notfluid)
Solidshaveno
translational
motion(only
vibration)

3. Typesofsolids
Basedonthestructure,Solidsareoftwotypes.
⚫Crystallinesolids:
Thesolidswhichhaverepetitiveordefinite
arrangementofatoms,moleculesandionsarebetterknownas
crystallinesolids.
Acrystallinesolidusuallyconsistsofalargenumberofsmall
crystals,eachofthemhavingadefinitecharacteristic
geometricalshape.Inacrystal,thearrangementofconstituent
particles(atoms,moleculesorions)isordered.
Sodiumchloride,Sugar,saltsandquartzaretypicalexamplesof
crystallinesolids.

4. ⚫Amorphoussolids:(noform)
Thesolidswhichdonothavedefiniteorrepetitivearrangementof
atomsandmoleculesareamorphoussolids.
Anamorphoussolidconsistsofparticlesofirregularshape.The
arrangementofconstituentparticles(atoms,moleculesorions)
randomandlackstheordered.
Example.silicon,plastics,wood,ceramicsandglass

5. Difference between
CrystallineandAmorphous solids
Property Crystallinesolids Amorphoussolids
Shape Definitecharacteristic
geometricalshape.
Irregularshape
Meltingpoint Melt at a sharp
andcharacteristic
Temperature.
Gradually softenovera
rangeoftemperature.
HeatoffusionTheyhaveadefinite
andcharacteristic
heatoffusion.
They do not have
definiteheatof fusion.
Nature Truesolids Pseudosolidsor
supercooledliquids.

6. Differencebetween
Crystalline andAmorphoussolids
i.e.,themagnitudeofsomeofthe
propertiesofcrystallinesolidslike
index;whileamorphoushave
properties,i.e.,themagnitudeof
physical
refractive
isotropic
physical
propertiesis sameinalldirections.
MeltingPoint
GeometricShape
CrystalSymmetry
Crystallinesolidspossessanisotropicproperties,
Propertiesvs.Direction

7. Propertiesofcrystalline solids
⚫Thecrystallinesolidsexhibitregularrepeatingstructure
representedbyunitcells.
symmetryof⚫Unitcellisthesmallestunitwithallthe
theentirecrystal
⚫Themorphologyofacrystallineformisoftenreferredtoas
itshabit,wherethecrystalhabitisdefinedashavingthesame
structurebutdifferentoutwardappearance.
⚫Theparticlesincrystalsarearrangedinregularpatternsthat
extendsinalldirections.Theoverallarrangementofparticles
inacrystalor3-dimensionalarrangementiscalledthe
Crystallattice,SpacelatticeorSimplylattice.
Lattice
UnitCell

8. Alatticeisof3types:
CRYSTALLATTICE

9. ⚫Thesesolidsusuallyshowspecificand sharpmeltingpoints
passingrathersharplyfromthesolidtotheliquidstate.
⚫Thediffractionsthroughthesecrystalsisfoundtobeverysharp.
⚫Thebreakageifanyisobservedonlyalongthe
crystallographicplanes.

10. TypesofCrystallinesolids
Crystallinesolidscanbeclassifiedonthebasisofnatureof
intermolecularforcesoperatinginthemintofourcategories.
Therearefourtypesofcrystallinesolids.
1.Ionicsolids
2.Molecularsolids
3.Metallicsolids
4.Covalentnetworksolids/Atomic
Solids

11. Typesofcrystallinesolids
Theunitsthatconstitutethecrystalstructurecanbeatoms,
molecules,orions
.
IonicSolid
Latticeunitsconsistof
ionsheldtogetherby
ionicbondsConduct
electricityonlyin
theirmoltenstate
e.g.NaCl
AtomicSolid
Latticeunitsconsistof
atomsheldtogetherby
covalentbonds.Bad
conductorofelectricity.
e.g.diamond
MolecularSolid
Latticeunitsconsists
ofmoleculesheld
togetherbyvander
Waalsforces.Weak
molecularattraction
Nonconductors
e.g. SolidCO2
Ionicandatomic crystalsingeneralarehardandbrittleandhavehighmelting
points,whilemolecularcrystalsaresoftandhaverelativelylowmeltingpoints.

12. Typesofcrystallinesolids
Metalliccrystalsarecomposedofpositivelychargedions
inafieldoffreelymovingelectrons.Theatomsareheld
togetherbymetallicbonding.
Metalsaregoodconductors
ofelectricitybecauseof
thefreemovementofthe
electronsinthelattice.
Metalsmaybesoftorhard
andhaveloworhigh
meltingpoints.

13. AmorphousSolids
Amorphoussolidsmaybeconsideredassupercooled
liquidsinwhichthemoleculesarearrangedina
somewhatrandommannerasintheliquidstate.
Amorphous Crystalline
Theydifferfromcrystallinesolidsinthattheytendtoflow
whensubjectedtosufficientpressureoveraperiodof
time,andtheydonothavedefinitemeltingpoints.

14. AmorphousSolids
Theamorphousstateisunstablecomparedtothe
crystallinesolid(ithashigherenergythancrystalline
solid).
Thepharmaceuticaladvantagesofamorphoussolidisits
highersolubilityandbioavailability.
Itspharmaceuticaldisadvantagesisitslowstability(over
time,amorphoussolidmaytransformtothemorestable
crystallinestate).

15. THEHABITOFACRYSTAL
The externalshapeiscalled thehabitofthecrystal.
The planesurfacesofthecrystalarecalledfaces.
Theanglesbetweenthefacesarereferredto astheinterfacialangles.
Theinterfacialanglesforagivencrystallinesubstancearealwaysthesame.
Theconsistencyofinterfacialanglesisanessentialcharacteristicofcrystalline
solids.
Thehabitofacrystalofagivencompounddependsontherateofdevelopmentof
thedifferentfaces.
Differentcrystalsofthesamesubstancemaynotlookalike.
Inthepresenceofcertainimpurities,differentfacesgrowatdifferentratesandgive
rise to manyforms.
Forexample,ifsodiumchlorideiscrystallizedfromitssupersaturatedsolution,it
formscubiccrystals.Butif ureaisaddedasimpurity,itgivesoctahedral crystals.
Interfacialangle
Cubic
Octahedral

16. SYMMETRYOFCRYSTALS
Symmetryincrystalsmaybeduetoaplane,alineorapoint.Accordinglythere
arethreetypesofsymmetryelementsassociatedwithacrystal.Thesearecalled
theElementsofSymmetry.
PlaneofSymmetry
Acrystalissaidtohaveaplaneofsymmetryifitcanbedividedbyanimaginary
planeintotwoequalparts,eachofwhichistheexactmirrorimageoftheother.
AxisofSymmetry
Anaxisofsymmetryisanimaginaryline
drawnthroughthecrystalsuchthat during
rotation of the crystal through 360º, the
crystalpresents exactlythesame
appearancemorethanonce.
CentreofSymmetry
Itis apointatthecentreofthecrystal
sothatanylinedrawnthroughitwill
meetthesurfaceofthecrystalatequal
distancesoneitherside.

17. DifferentCrystalSystems