States of Matter

• Kinetic Molecular Theory: the idea that particles of matter are always in motion; this applies to all states of matter

• Used to explain properties of matter in terms of energy

Ideal Gas= hypothetical gas that perfectly fits all 5 assumptions of

the Kinetic Molecular Theory:

1) Gases consist of a large # of particles that occupy a larger space with respect to their relative sizes

thus gases can be easily compressed

2) Collisions b/t particles and walls are perfectly elastic ( = no loss of KE)

3) Gas particles are in rapid, random, constant motion4) There are no forces of attraction b/t gas particles5) Temperature of a gas depends on the average

KE of the particles; directly proportional

A gas that is always a gas - Doesn’t exist!

Characteristics of Gases

• Expansion: no definite shape or volume; fill any container, regardless of shape

• Fluidity: particles slide easily over one another; act like liquids, thus they are both fluids

• Low Density and Compressibility: volume can be decreased greatly

• Diffusion: since gases are always randomly moving, freely mix together with other gases

• Effusion: process by which gases move out of a small opening; molecules with low mass effuse more quickly than those with larger masses

KE= ½ mv2

Liquids

• Least common state of matter in universe; not so on Earth

• Operate at slim range of temps/pressures

• Volume, shape, density?• Particles in constant

motion, and closer than those of a gas (intermolecular forces)

Other Characteristics of liquids:• Have a very high density when compared to

gases; depends on temperature lower temp…except for water

• Not easily compressed

• Easily diffuse in other liquids it can dissolve in d/t… much slower than it is in gases

Surface Tension

• All liquids exhibit surface tension = a force that tends to pull adjacent particles at a liquids surface together, decreasing its surface area to the smallest possible size; meniscus

• Results from… water shows high surface tension

• Capillary action = attraction of a liquid to a solid; rises in a small tube against gravity

Surface TensionLook at the picture below. The milk forms small droplets that

resemble a crown. But why does this happen?

Because of the surface tension of water, which keeps the

droplets spherical.

Some terms:

solid liquid gasMELTING BOILING

FREEZING CONDENSATION

0ºC 100ºC

melting/freezing point boiling/condensation point

(ice) (steam)(water)

SUBLIMATION

More info on Liquids• Vaporization – liquid to

gas• Evaporation – escape

from a non-boiling liquid at its surface

• Boiling – vaporization through the entire liquid

• Freezing – physical change from liquid to solid through the loss of HEAT. Evaporation- a beautiful process.

Solids

• Particles in a solid are tightly-packed together due to attractive forces. Highly-ordered.

• Atomic/molecular motion is restricted, but it occurs.

• 2 types:1) Crystalline: consists of crystals

(orderly, geometric, repeating pattern)

2) Amorphous: particles are randomly arranged

Sodium Chloride crystals

Amorphous solid

Properties of solids• Definite shape and volume

• Definite melting point (d/t addition of heat)

• High density and incompressible

• Low rates of diffusion

Crystals• Arranged in a lattice structure

• Smallest unit of a crystal that shows the 3-D pattern of the lattice = UNIT CELL

Changes of State

• Phase = any part of a system that has a uniform composition and properties

• Condensation = process by which a gas turns into a liquid

• Vapor = a gas in contact with its liquid or solid phase

Vapor Pressure

• The pressure exerted by a vapor that is in equilibrium with its corresponding liquid

• Develops in a closed system

• Increase AKE, increase particles leaving liquid, increased pressure

• Volatile liquids evaporate

easily d/t weak IMF

Vapor Pressure

Notes on Boiling Point• BP = when vapor pressure

equals atmospheric pressure• Increase pressure, increase

BP = pressure cooker• Molar Enthalpy of

Vaporization = amount of heat needed to vaporize 1 mole of a liquid at the liquid’s BP at a constant pressure; the stronger the attraction….

• Vapor pressure is directly proportional to temperature

Freezing and Melting• Definitions?

• What is the difference b/t freezing water and ice? Boiling water and steam?

Do Now• Explain the importance and significance of

this graph…

More Vocab

• Molar Enthalpy of Fusion = the amount of heat required to melt one mole of a solid

(40.79 kJ/mol for water)

• Sublimation vs. deposition

Phase Diagrams graph of pressure vs. temperature that shows the conditions

under which the phases of a substance would exist

Water• Most abundant liquid

on Earth; essential to life; most reactions take place in it IMPORTANT!!!

• Review its structure and properties…

Water