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Unit 3 Intermolecular forces and properties - Coggle Diagram
Unit 3 Intermolecular forces
and properties
3.3 Solids, liquids and gases
3.2 properties of solids
liquid
they are continually moving and colliding
constituent particles in are in
close contact with each other
The arrangement and movement of particles are influenced by the nature and strength of the forces between particles
gas
Their frequencies of collision and the average spacing between them are dependent on temperature (T), pressure (P), and volume (V)
minimal effects of forces between particles
particles are in constant motion
no definite volume nor a definite shape
solids
motion of the individual particles is limited
particles do not undergo overall translation with respect to each other
crystalline vs amorphous
The structure of the solid is influenced by:
a. interparticle interactions
b. the ability of the particles to pack together.
properties of solids
Melting points
also tend to correlate with interaction strength (the relations can be more subtle because the interactions are rearranged)
ionic solid
low vapor pressure, high mp, high bp.
brittle, conduct electricity when
melted or dissolved in water
Lattice energy: 1. larger charge 2. smaller ions
the vapor pressure and boiling point are directly related to the strength of those interactions. (intermolecular interactions are broken)
covalent network solid
Strong covalent interactions
high m.p, rigid and hard, do not conduct electricity
graphite conducts electricity along the layers
molecular solid
weak intermolecular force
low m.p, do not conduct electricity
metallic solid
good conductors of electricity and heat, malleable and ductile
alloy
Interstitial alloy:
make the lattice more rigid, decreasing malleability and ductility
substitutional
alloy
Particulate-level representations
3.1 intermolecular forces
dipole-induced dipole force
between a
polar and nonpolar molecule
.
These forces are always
attractive.
The strength of these forces increases with:
a. the magnitude of the dipole of the polar molecule
b. the polarizability of the nonpolar molecule.
dipole-dipole force
between
polar molecules
(caused by permanent dipole).
The interaction strength depends on:
a. the magnitudes of the dipoles
b. their relative orientation (both attraction and repulsion).
LDF:
Dispersion forces increase with increasing:
a.
contact area
between molecules
b.
increasing polarizability
of the molecules
The polarizability of a molecule increases with an
increasing number of electrons
in the molecule; and the
size of the electron cloud.
It is enhanced by the presence of pi bonding
Coulombic interactions between
temporary, fluctuating dipoles
Exist in all matter
ion-dipole force
between ions and polar molecules.
These tend to be stronger than dipole-dipole forces.
hydrogen
bonding
hydrogen atoms covalently bonded to the highly electronegative atoms (N, O, and F)
H attracted to the negative end of a dipole formed by the electronegative atom (N, O, and F)
3.4 ideal gas law
3.5 KMT
3.6 deviation from ideal gas law
KMT
kinetic molecular theory (KMT) relates the macroscopic properties of gases to motions of the particles in the gas.
Maxwell-Boltzmann distribution
Gram's law: rate of effusion for gas: inversely proportional to the square root of molar mass
deviation from ideal gas results from:
interparticle attractions at low temperature.
particle volumes particularly at extremely high pressures.
ideal gas law
PV=nRT, PM=DRT
partial pressure: Ptotal = PA + PB + PC + …
PA = Ptotal × XA, where XA = moles A/total moles;
Graphical representations of the relationships between P, V, T, and n
3.7 solutions and mixtures
3.8 representations of solutions
3.9 separation of solutions
and mixtures
3.10 solubility
solution is also called homogeneous mixture
molarity M= n(solute)/V(solution)
representations
of solutions
relative concentrations of the components
interactions between components:
ion sizes & orientation of solute ions and solvent particles
separation
of mixtures
Filtration:
for heterogeneous, based on difference in particle size
Chromatography:
differential strength of intermolecular interactions between and among the components of the solution (the mobile phase) and with the surface components of the stationary phase.
Distillation
: based on
intermolecular interactions
and the
vapor pressures
of the components in the mixture.
solubility: like dissolves like
Substances with similar intermolecular interactions tend to be miscible or soluble in one another.
3.11 spectroscopy and
electromagnetic spectrum
Infrared radiation is associated with transitions in
molecular vibrational
levels
Ultraviolet/visible radiation is associated with
transitions in electronic energy levels.
Microwave radiation is associated with transitions in
molecular rotational
levels.
3.12 photoelectric effect
E = ℎν
c = λν
3.13 Beer-Lambert law
A is proportional to concentration when path length (b) and wavelength are held constant
obtain concentration from A and calibration plot
A = Ɛbc.