states of matter Flashcards
what are the 3 types of intermolecular forces?
-dispersion forces (London dispersion forces)
-dipolar forces (dipole-dipole interactions)
-hydrogen bonds
what are London dispersion forces?
-attraction arising from the constant motion of electrons
-temporary change imbalance leads to a weak interaction between neighbouring particles
what are dipole-dipole interactions?
-attractions between oppositely charged ends of neighbouring molecules
what are hydrogen bonds?
attraction between the lone pair of electrons on N,O or F atoms and a hydrogen atom
what are the two requirements for hydrogen bonding to occur?
-there needs to be an electron deficient hydrogen atom that can be attracted to an electron pair
-there has to be a highly electronegative atom with an electron pair that can interact with the electron deficient hydrogen atom
what was Boyle’s law?
-he stated thavolume was inversely proportional to pressure
-pV=constant or p1V1=p2V2
what is the ideal gas equation?
pV=nRT
what are the different units for the ideal gas equation?
p=Pa
V=m3
n=mol
T=K
R=8.314 Jmol-1 K-1
what are the therapeutic uses of gases?
they can be used medically e.g
-oxygen (for hypoxia) e.g respiratory failure
-heliox (for hypoxia)-mixture of 21% O2 and 79% He
-entonox which is used in analgesia it consists of 50% N2O and 50% O2
what are the properties of liquids?
-the intermolecular forces are strong enough to confine the molecules to a specific volume
-molecules are able to move freely
-liquids cannot expand or contract significantly
what is capillary action?
-the upward movement of movement of water against the downward force of gravity
what is viscosity?
-a liquids resistance to flow
-it measures how easily molecules slide by one another
-the greater the viscosity, the more slowly the liquid pours
what can viscosity be affected by?
-molecular shape and the strength of the molecular forces
-temperature
what are emulsions?
-mixtures with immiscible liquid droplets dispersed within a second liquid phase
what do suspensions consist of?
-particles dispersed in a liquid
-the solid phase is dispersed in a liquid phase
what type of systems are suspensions and emulsions?
heterogenous systems
what can the parenteral dosage form consist of?
-intramuscular (IM)
-subcutaneous (SC)
-intravenous (IV)
what are the different liquid dosage forms?
-oral
-topical
-ocular
-nasal
-otic-ear
-aerosol
-parenteral
what are the different types of solids?
-molecular solids
-network solids
-ionic solids
-metallic solids
what do molecular solids consist of?
-aggregates of molecules bound together by intermolecular forces
-the forces can be dispersion,dipolar,hydrogen bonding or a combination of-many larger molecules have sufficient dispersion forces forced to exist as solids at room temp
what is an example of a molecular solid?
-crystals of benzoic acid that contain pairs of molecules held together by hydrogen bonds
-the pairs then stack in planes which are held together by dispersion forces
what are examples of network solids?
-graphite-has sp2 hybridisation and a planar trigonal arrangement
-diamond-has sp3 hybridisation and a tetrahedral structure
what are the properties of network solids?
-high melting points
-eld together by covalent bonds that are harder to break than intermolecular forces
-covalent bonds Mae network solids extremely durable
-the bonding patterns determine the properties of these solis
what are the stoichiometries of ionic solids determined by?
-the charges carried by positive and negative ions
-the solids adopt a variety of structures depending on the stoichiometry and relative sizes of the ions
what do ionic solids contain?
-cations and anions strongly attracted to each other by electrostatic forces
-many also contain metal cations and polyatomic anions
-the cations and anions are usually different sizes
what causes ionic solids to have high melting points?
-strong electrostatic interactions between the ions
why does the packing in ionic crystals require?
-that ions of opposite charge alternate with each other to maximise attractions and minimise repulsions
how are amorphous solids formed?
-by solids forming rapidly which means their atoms, ions or molecules may become locked into positions other than those of a regular crystal and these materials are said to be without form so amorphous
what is an example of an amorphous solid?
-glass is an entire family of amorphous solid based on silica
-amorphous solids do not diffract x rays
what are the advantages of solid dosage forms via the digestive tract?
-it allows for consistent quality and dosing
-it allows for enhanced mechanical/chemical stability
-it lends for adaptation e.g coatings
-has good patient compliance
how are dosage forms taken via the digestive tract prepared?
-usually by compression of powders/granules
-excipients are added such as diluents to ensure tablets are an appropriate size as an antioxidant and/or as a disintegrant
what is a phase change?
-the transition of a substance from one phase to another
what do phase changes depend on?
-temperature
-pressure
-magnitude of intermolecular and bonding forces
look at the diagrams for this lecture
