STATES OF MATTER

Chemistry CP

EnergyPotential Energy: Stored Energy

If you heat a substance, that substance will store some of that energy in its particles

Kinetic Energy: Energy of Motion

Kinetic Energy: Increases in kinetic energy result in increases in temperature

•Heat added to a system that is not stored as potential energy will be absorbed by the particles which will increase the particles’ kinetic energy

Absolute Zero (0 K): The temperature at which the motion of particles theoretically ceases and the particles have no kinetic energy

Kelvin Scale: Reflects the relationship between temperature and average kinetic energy

•Directly proportional to the kinetic energy of the particles

All matter consists of tiny particles that are in constant

motion

Hydrogen Bonding: The large partial charge resulting in an extremely strong dipole-dipole force between hydrogen of on molecule (+) and the F, O or N of another molecule (-)•One of the strongest intermolecular forces

Dipole-Dipole Forces: Attractions between opposite charges of neighboring permanent dipoles•Happens between polar molecules

Dispersion Forces: A force of attraction between induced dipoles•Induced dipoles occur when a temporary dipole occurs (the e- move to one side of an atom simply through their natural movement)•Can happen between nonpolar molecules

Strength

SOLID LIQUID •GAS

•Ionic, Metallic or Molecular Bonds (Strong Bonds between atoms)•Atoms, ions or molecules are packed tightly together•Particles vibrate around fixed points•Crystalline or Amorphous Solids•Do not flow•Condensed state of matter (pressure has little effect on a solid)•Only slightly compressible•High density•Extremely slow diffusion (only occurs at surface)•Definite volume•Definite shape

•Molecules or Atoms•Intermolecular forces keep the particles in a liquid close together•Intermolecular forces reduce the amount of space between the particles•Condensed state of matter (pressure has little effect on a liquid)•Can flow (a fluid)•Only slightly compressible•High density•Does not expand to fill the container•Assumes the shape of the container•Slow diffusion•Definite volume•No definite shape

•Molecules or Atoms•Particles are small, hard spheres with insignificant volume•Particles are far apart with empty space between them•No attractive or repulsive forces between particles•Motion of one particle is independent of the rest•Motion of particles is rapid, constant and in straight line paths until they collide•Perfectly elastic collisions (kinetic energy remains constant)•Can flow (a fluid)•Can be compressed•Low density•Fills container completely•Assumes shape of container•Rapid Diffusion•No definite volume nor shape

Gas Pressure: The force exerted by a gas

per unit surface area of an object

•Caused by the collisions of the moving gas particles

with an object

Vacuum: An empty space with no particles

and no pressure

Atmospheric Pressure:

Results from the collisions of

atoms and molecules in air

with objects

Barometer: Device that is used to measure atmospheric pressure

Pascal (Pa): SI unit of

pressure

mm Hg: Unit on a barometer

atmosphere: Pressure

required to support 760 mm

Hg in a mercury barometer at

25C

Standard Temperature & Pressure (STP): Temperature of 0C and 1 atm

LIQUIDS Vapor Pressure: A measure

of the force exerted by a gas

above a liquid At equilibrium: The rate of evaporation of the liquid

equals the rate of condensation of the vapor

MANOMETER: Measures the vapor pressure of a

contained liquid

Affect of Temperature on Vapor Pressure

An increase in temperature of a contained liquid will increase the vapor pressure because the kinetic energy will increase resulting in more particles escaping the surface of the liquid.

VISCOSITY

A liquids resistance to motion

• Liquids with stronger intermolecular forces will have higher viscosities– Water’s viscosity

is relatively high due to its hydrogen bonding

– Lower temperatures = higher viscosity

SURFACE TENSIONImbalance of attractive forces at the surface of a liquid that

causes the surface to behave as if it had a thin film across itGreater in liquids with strong intermolecular forces

SOLIDS• Crystals: The particles are

arranged in an orderly, repeating, 3-dimensional pattern called a crystal lattice– The shape of the crystal

reflects the arrangement of the particles within the solid

• Unit Cell: The smallest group of particles within a crystal that retains the geometric shape of the crystal

SOLIDS

Amorphous Solids: Lacks an ordered internal structure• Plastic, rubber,

glass, asphalt

Change of StateConversion of a substance from one of three physical states of matter to another.• A.k.a: Phase Change• Always involves: A change in energy

Energy & State Changes

Gases have the most potential energy, solids the least

VAPORIZATION: The change of state from a liquid to a gas

•Evaporation rates increases with increases in temperature because the increase in energy allows more molecules to escape the surface of the liquid

•The molecules remaining behind in the liquid are lower in energy

Evaporation: Molecules at the surface of a liquid escape and enter the gas phase

Boiling: When the vapor pressure of the liquid is equal to the atmospheric pressure, bubbles of gas form and escape the liquid.

Boiling Point: The temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure

Normal Boiling Point: The boiling point of a liquid at a pressure of 101.3 kPa (normal atmospheric pressure)

If atmospheric pressure increases, the temperature needed to reach the boiling point will also increase. If atmospheric pressure decreases, the

temperature needed to reach the boiling point will also decrease.

CONDENSATION

• The change of state from a gas to a liquid

FREEZINGThe change of state from a liquid to a solid.

Freezing Point: The temperature at which the solid and liquid forms of a substance exist in equilibrium

MELTING

• The change of state from a solid to a liquid

• Melting Point: The temperature at which a solid changes into a liquid– Equals: The freezing point

Sublimation: The

change of state from a

solid to a gas

Deposition: The change of state from a gas to a solid

Typically occurs with molecular solids with weak intermolecular

forces.

HEATING CURVE

During a state change, the temperature remains constant while the potential energy increases/decreases. This will occur until the state is completely changed and then kinetic energy will begin to increase/decrease again.

Phase DiagramRelates the state of a substance to its temperature and pressure.

•Triple Point: The only set of conditions at which all three phases can exist in equilibrium with one another

For water, the triple point is 0.016C and 0.61 kPa/0.0060 atm