Chapter 13-States of Matter

Chem 311

Kinetic Theory All mater consists of tiny particles that

are in constant motion Specifically, the particles in gas are

considered to be small hard spheres with an insignificant volume

The particles in gas are spread out leaving a lot of open space

Gas Particles The motion of particles in a gas is

rapid, constant, and random As a result gases will always

spread out and fill the area they are contained in

The particles travel in a straight line but change course after collisions with other gas molecules

During collisions kinetic energy is transferred from one particle to the other without loss as the collisions are characterized as elastic

Kinetic Theory of Gases

A gas is composed of a large number of molecules that are very small relative to the distance between molecules.

The molecules of a gas are in constant, random motion and frequently collide with each other and with their container.

Measuring Air Pressure

A Barometer is a device used to measure atmospheric pressure and can be read the same way as a thermometer.

The height of the mercury in a barometer depends on weather and altitude. The higher the altitude, the lower the pressure.

The atmospheric pressure pushes the mercury from the reservoir into the glass tube. The pressure at sea level is 760mm, or 29.2 inches. The tip of the tube is a vacuum- an empty space with no pressure or particles.

Gas Pressure

Gas Pressure is the result of simultaneous collisions of billions of rapidly moving gas particles against an object. The more collisions, the higher the pressure.

The collision / movement of these gas particles can be explained with the Kinetic theory (which states that matter consists of tiny particles in constant motion).

The Pascal (Pa) is the SI unit of pressure, another unit of measurement is millimeters of mercury (mm Hg) and standard atmospheres (atm).

Kinetic Theory + Distribution Curve

Increase in kinetic energy= increase in temperature

Higher temperature has wider range of kinetic energies

Increase in avg kinetic energy causes a rise of the temperature

Kelvin

At absolute zero (0 K) particles have no kinetic energy/no motion. There is no lower temperature than absolute zero Kelvin.

Kelvin temperature is directly proportional to the avg kinetic energy of a substance For example, particles

of helium at 200K have 2x the avg kinetic energy as helium at 100K

A Model for Liquids

Both the particles in gases and the particles in liquids have kinetic energy.

This energy allows the particles in gases and liquids to flow past each other.

Substances that can flow are known as fluids.

Since fluids flow the way they do, they conform to the shape of their containers.

Pt. II Unlike the particles of gases, inter-molecular attractions

reduce the amount of space between the particles in liquids.

Since the particles of liquids are close together, liquids have a definite volume.

Liquids are consequently much more dense than gases Changing the amount of pressure on a liquid hardly

effects its volume. Since liquids and solids are mostly incondensable, they

are known as condensed states of matter.

Solid Organization and PropertiesSolid Organization and Properties Closely packed ions, atoms, or Closely packed ions, atoms, or

molecules, well organizedmolecules, well organized Particles have fixed location and vibrate Particles have fixed location and vibrate

around fixed points, strong attractionsaround fixed points, strong attractions Solids do not flowSolids do not flow

Dense (not easily compressed)Dense (not easily compressed) Melting pointsMelting points

Ionic solids- high melting pointIonic solids- high melting point Molecular solids- low melting pointMolecular solids- low melting point

Melting Point of SolidsMelting Point of Solids

melting point-melting point-temperature where solid changes temperature where solid changes into a liquidinto a liquid When melted, solid particles have high When melted, solid particles have high

vibrations that allow them to move out of vibrations that allow them to move out of fixed positions and into liquid formfixed positions and into liquid form

Equilibrium- Equilibrium- temperature where melting temperature where melting point of solid and freezing point of liquid are point of solid and freezing point of liquid are at same temperatureat same temperature

Melting point is determined by particle Melting point is determined by particle organizationorganization

Solid melting point exceptionsSolid melting point exceptions Cane sugar and woodCane sugar and wood

Crystal Structures and SystemsCrystal Structures and Systems

Crystal-Crystal- three dimensional pattern arrangement of three dimensional pattern arrangement of solid particlessolid particles

Crystal shape describes solid particle arrangementCrystal shape describes solid particle arrangement Crystal propertiesCrystal properties

Has sides or faceHas sides or face Labeled a, b, cLabeled a, b, c

Has angles that intersect at facesHas angles that intersect at faces Labeled β, Υ, αLabeled β, Υ, α

Seven groups of crystals- cubic, tetragonal, Seven groups of crystals- cubic, tetragonal, rhombic, monoclinic, triclinic, hexagonal, and rhombic, monoclinic, triclinic, hexagonal, and rhombohedrarhombohedra

Liquid Organization and PropertiesLiquid Organization and Properties Contain kinetic energyContain kinetic energy Fluids-Fluids- particles that flow particles that flow

Allows liquids to take shape of containerAllows liquids to take shape of container Particles have relatively strong attractionsParticles have relatively strong attractions

Keep particles togetherKeep particles together Create definite volumeCreate definite volume Keeps particles close togetherKeeps particles close together

Denser than gases, less dense then solidsDenser than gases, less dense then solids Not effected by pressureNot effected by pressure

Gas Organization and PropertiesGas Organization and Properties

Particles have kinetic energy (like liquids)Particles have kinetic energy (like liquids) Keeps particles in constant motionKeeps particles in constant motion

Particles are small hard spheres with Particles are small hard spheres with insignificant volumeinsignificant volume Spacing is highSpacing is high No attractive forces to hold them togetherNo attractive forces to hold them together

Particles are in constant motionParticles are in constant motion Fill container regardless of shapeFill container regardless of shape

Attractive forces

Organization of particles

Gases No Particles in constant motion

Liquids Yes, slightly strong

Takes shape of container

Solids Yes, very strong

In crystal structures

Solid Liquid Gas Organization and Solid Liquid Gas Organization and AttractionAttraction

Distinguishing Between Crystal and Distinguishing Between Crystal and GlassGlass

Properties of CrystalProperties of Crystal Particles are arranged in an orderly, 3-D pattern called a Particles are arranged in an orderly, 3-D pattern called a

crystal latticecrystal lattice Has sides, or facesHas sides, or faces In general, have high melting points (unless molecular)In general, have high melting points (unless molecular) When shattered, fragments have the same surface angles When shattered, fragments have the same surface angles

as the original solidas the original solid Properties of GlassProperties of Glass

Also called amorphous solidAlso called amorphous solid Crystallization does not occurCrystallization does not occur The structures of glasses are intermediate between those of The structures of glasses are intermediate between those of

crystalline and those of free-flowing liquidscrystalline and those of free-flowing liquids Do not melt at a definite temp.Do not melt at a definite temp. When shattered, fragments have irregular angles and When shattered, fragments have irregular angles and

jagged edgesjagged edges

Crystal vs. Glass StructuresCrystal vs. Glass Structures

CrystalCrystal The shape of a crystal reflects The shape of a crystal reflects

the arrangement of particles the arrangement of particles within the solidwithin the solid

The smallest group of particles The smallest group of particles that retains its geometric shape that retains its geometric shape is the unit cellis the unit cell The unit cell may be simple cubic, The unit cell may be simple cubic,

body-centered cubic, or face-body-centered cubic, or face-centered cubiccentered cubic

GlassGlass Glasses or, amorphous solids, Glasses or, amorphous solids,

are transparent fusion products are transparent fusion products of inorganic substances that of inorganic substances that have cooled to a rigid state have cooled to a rigid state WITHOUT crystallizingWITHOUT crystallizing

Different Shapes of Crystal SystemsDifferent Shapes of Crystal Systems

Sublimation

When a solid becomes a gas without passes through the liquid state.

Occurs when a solid has a vapor pressure higher than the pressure at or near room temperature.

Vapor pressure: the measure of a force exerted by a gas above a liquid (true for solids too)

Deposition

When a gas becomes a solid without passes through the liquid state.

Phase diagram-shows the conditions and pressure at which a

substance exists as a solid, liquid, and gas

Triple point- the only set of conditions where all three states can exist.

Critical point- beyond this region the physical and chemical properties of water and steam converge to the point where they are identical. Thus, beyond the critical point, we refer to this single phase as a "supercritical fluid".

Boiling, melting, and subliming curves

Plasma: What is it?

Most common state of matter Electrically charged particles at high energy that

collect around electromagnetic fields and form gas-like clouds

It is made of extremely hot ions and electrons in space, but on Earth, it cools into atoms and molecules

The particles are affected by electromagnetic, electric, and magnetic signals but are hardly affected by gravity.

Plasma: What is it? (cont.)

The full range of plasma’s density, temperature, and spatial scales is nearly incomprehensible as it is so wide and varied.

Without sufficient energy, the plasma reverts back to a neutral gas

Energy being thermal, electrical, or light (i.e. ultraviolet)

Ions and electrons move independently in large spaces

Plasmas are still being studied and understood today

Plasma Examples

Flames neon signs Nebulae (Clouds in space) solar wind Auroras Galaxies dense solid state of matter Stars Space Lightning florescent lights