PART 6:
Chemistry Properties of Matter
STATES OF MATTER:
SOLID:
~fixed volume and shape
~The particles of solids vibrate but stay in a relatively fixed position
~Crystals form if the particles are arranged in a regular sequence
LIQUID:
~fixed volume but take the shape of the container
~The atoms move relative to one another but still stay close together
~Liquids can only exist for a limited temperature range
GAS:
~Gases have no fixed volume or shape; they expand to fill all available space and can be compressed
~Atoms in a gas are free to move independently from each other
PLASMA
~gas that has ionised due to very high temperature
~The particles are electrically charged and is affected by magnetic and electric fields
CHANGES OF STATE:
Matter can change between states
when the temperature or pressure of a system is changed
PHASE CHANGES:
~Heating causes the particles of matter to absorb energy, move more vigorously and separate further apart
~Cooling causes the particles to move less vigorously and come closer together
A phase diagram:
shows the various phases (or states) of a system as a function of pressure and temperature
The critical point:
Above this critical temperature and critical pressure the liquid and vapor are indistinguishable from each other.
The triple point:
the point at which all three states are in equilibrium
The sublimation point curve (or sublimation point line):
A line where the solid and the gas phase are in equilibrium
The boiling point curve (aka vapor pressure curve):
A line where the liquid and gas phase are in equilibrium
The melting point curve
(aka fusion curve):
A line where the solid and the liquid phase are in equilibrium
variables are used to measure gases:
Pressure
Volume
Temperature
BOYLES'S LAW:
The "volume" of a given mass of a gas is inversely proportional to "pressure" at constant temperature
CHARLES LAW:
The "volume" of a given mass of a gas is proportional to absolute "temperature" at constant pressure
GAY-LUSSACE'S LAW:
The "pressure" of a given mass of a gas is proportional to absolute "temperature" at constant volume
AVOGADRO'S LAW:
The "volumes" of gases are proportional to the number of "atoms or molecules"
The Ideal Gas Law:
The volumes of gases are proportional to the number of atoms or molecules
"(PV = nRT)"
We derive the Combined gas Law by equating two sets of Ideal Gas Laws at two conditions
Dalton's Law of Partial Pressure
determining the actual pressure of a gas collected by the water displacement method
Graham's Law of Effusion (Diffusion):
The rate of "effusion" of a gas is inversely proportional to the square root of its "density"
Diffusion:Rate at which two gases mix
Effusion:Rate at which a gas moves through a small hole
The Kinetic Theory of Gases:
Gases are compressible
(The volumes of gas particles are negligible [very small])
Gas particles do not influence each other and fills up a container
(Intermolecular forces do not exist between gas particles)
Gas particles collide with one another and the walls of a container without energy lose
(Gas particles move in random motions and collide without energy loss [elastic collisions])
Gas is heated the particles move faster
(The kinetic energy of a gas is directly proportional to absolute temperature)
PROPERTIES OF LIQUID
Viscosity:
measure of the resistance to flow
Surface tension:
The force that controls the shape of the liquid is called the surface tension
The vapor pressure:
the pressure of the vapor (gas) above the liquid at a given temperature
Colligative properties:
Properties of solutions that depend solely on the number of particles dissolved in the solution
Vapor pressure:
The vapor pressure of a solution containing nonvolatile solute is "lower" than the pure solvent (Raoult's Law)
Boiling point:
The boiling point of a solution containing nonvolatile solute is "greater" than the boiling point of the pure solvent
Freezing point depression:
The freezing point of a solution containing nonvolatile solute is "lower" than the boiling point of the pure solvent
Osmotic pressure:
The back pressure (or opposing pressure) needed to prevent osmosis "(selective passage of solvent molecules through a porous membrane from a dilute solution to a more concentrated one)"
types of solids:
Crystalline solids:
~The atoms, molecules or ions are arranged in a regular pattern
~They exhibit anisotropic properties
~They have sharp (specific) melting points
Ionic crystals:
~Consist of positive and negative ions alternately arranged
~Have high melting points, tend to be hard or brittle
~Conduct electricity in the molten or soluble state
Molecular crystals:
~Consist of uncharged atoms/molecules
~Have low melting points and tend to be soft
~Non conductors
Covalent crystals:
~A network of covalently bonded atoms forming a gigantic molecule
~Have high melting points and tend to be hard
~Non conductors
Metallic crystals:
~Consist of positive metal ions
~Melting points and hardness depend on the nuclear charge and electrons
~Conductors
Amorphous solids:
~Particles have no regular pattern of arrangement
~Melt over a range of temperatures
Unit cell:
the smallest basic unit of a crystal that can be repeated in three dimensions throughout the crystal lattice
Crystal lattice:
The repeating pattern of particles in a crystalline solid
Crystal system:
Method of classifying crystalline substances on the basis of their unit cell
1.Cubic
2.Tetragonal
3.Orthorhombic
4.Monoclinic
5.Triclinic
6.Hexagonal
7.Rhombohedral
Atomic radius and Density:
The radius of an atom can be calculated from the crystal structure of a substance using data obtained from a method known as X-ray analysis
A solid crystal is built up by placing closed packed layers of spheres