Download STATE of MATTER

STATE of MATTER
Dr. Nermeen Adel
SOLID, LIQUID and GAS
are the most common
states of matter on Earth.
Gases
•
Gas molecules have enough
KINETIC ENERGY so that the
effect of intermolecular forces is
small.
• A gas has NO DEFINITE shape or
volume, but occupies the entire
container in which it is confined
• A Supercritical Fluid has the
physical properties of a gas, but its
high density confers solvent (liquid)
properties i.e. supercritical carbon
dioxide (solvents). Gases assume the volume and shape of
the container. Gases are the most
compressible state of matter
Liquids
• A liquid is a nearly incompressible FLUID that
conforms to the shape of its container but retains
a (nearly) constant volume independent of
pressure.
• Intermolecular forces are important, but the
molecules have enough energy to move relative
to each other and the structure is mobile.
Liquids
The highest temperature (at
constant pressure)at which a
given liquid (water) can exist
is
CRITICAL TEMPERATURE
Solids
• Their particles (ions, atoms or
molecules) are PACKED CLOSELY
together. The forces between them
are STRONG enough so that they
cannot move freely but can only
vibrate.
• A solid has a stable, definite shape,
and a definite volume.
• Solids can be changed into liquids
by melting, and liquids can be
transformed into solids by freezing.
They can also change directly into
gases through the process of
sublimation.
Solids
Types of SOLIDS
• CRYSTALLINE
• AMORPHOUS
Crystalline solid
FORCES BETWEEN SOLID ATOMS
IONIC BOND
A crystal of sodium chloride
(common salt) is made up of
ionic sodium and chlorine
COVALENT BOND
In diamond or silicon, the atoms
share electrons .
ORGANIC COMPOUNDS, are held
with Van der Waals forces resulting
from the polarization of the
electronic charge cloud on each
molecule.
Characterization of Crystalline Materials
BY:
• X-ray diffraction
• Melting points
• Polymorphs
Amorphous solid
It refers to materials with NO particular structure (lack
of form). The atoms or molecules of amorphous
materials are arranged in the SAME manner as they
are in a liquid.
They have increased mobility due to greater
intermolecular distances. We can say that an
amorphous system is actually fluid but appears to
be a solid
Properties of Amorphous Solid
*** The molecules are closely packed &
chemically bonded.
*** Any material can be prepared as an
amorphous solid. All amorphous materials have
crystalline counterparts.
*** Crystalline form will generally be more stable
than the amorphous one, as the crystalline solid
is at chemical equilibrium, whereas the
amorphous form is not.
Polymorphs
• The molecules arrange themselves in two or
more different ways in the crystal. They are
arranged either differently in the crystal lattice or
there may be differences in the orientation of the
molecules at the lattice sites.
• The polymorphs have different Physical and
Chemical properties; i.e. different chemical
reactivity, different melting points, solubilities.
• Formation of polymorph by a drug depends on
the conditions of crystallization; i.e. , the
solvent used, the rate of crystallization and the
temperature.
Polymorphism problems in pharmaceutical preparations
• It may be difficult to inject in suspension form or
to formulate as tablets.
• Change between polymorphic forms during
storage can cause changes in crystal size in
suspensions and their eventual caking.
• Crystal growth in creams as a result of phase
transformation can cause the cream to become
gritty.
Cont.
• Changes in polymorphic forms of vehicles such
as theobroma oil (cocoa butter), used to make
suppositories, could produce supp. with different
and unacceptable melting characteristics.
COCOA BUTTER
COCOA BUTTER is single glyceride, used as
suppository base, it melts (34 oC – 36 oC).
It has 4 polymorphic forms:
• meta stable gamma form melting at 18 oC
• alpha form melting at 22 oC,
• beta prime form melting at 28 oC
• stable beta form melting at 34.5 oC
Proper Method of Preparation
COCOA BUTTER
• Melt cocoa butter at the lowest possible
temperature, about 33oC.
• Pour when sufficiently fluid; SO the crystal nuclei
of the stable beta form are not lost.
• When the mass is chilled in the mold, a stable
suppository, consisting of beta crystals, which
melt at 34.5oC, is produced.
Liquid crystals (LCs)
• It is state of matter that have properties between
those of a conventional liquid and those of a
solid crystal.
• Liquid crystal may flow like a liquid, but its
molecules may be oriented in a crystal-like way
like a solid.
• Liquid crystals can be divided into Thermotropic
Lyotropic and Metallotropic phases.
Liquid crystals (LCs)
Thermotropic
It exhibits a Phase Transition into the
liquid crystal phase as Temperature is
changed. (organic)
Lyotropic
It exhibits Phase Transition as a
function of both Temperature and
Concentration of the liquid crystal
molecules in a Solvent (typically
water). (organic)
Metallotropic
Their liquid crystal Transition depends
not only on Temperature and
Concentration, but also on the
inorganic-organic composition ratio.
(inorganic & organic)
Applications of liquid crystals
• In birefringence, the light passing through a
material is divided into two components with
different velocities and hence different refractive
indices.
Describes how
• Some liquid crystals show consistent color
light propagate
changes with temperature, so they are used
through
medium
to detect areas of elevated temperature under
the skin that may be due to a disease process.
• Liquid crystals are sensitive to electric fields, a
property of advantage in developing display
systems. (LCD)
Ionic bond : attraction between
complete positive and negative charge
Van der Waals forces : attraction
between partial positive and partial
negative charge
So, it is weaker than the ionic bond