States of Matter The nature of gases, liquids & solids is all about the motion of the particles.

SolidLiquidGas Movement of particles Rotate & vibrate Have “flow”-can move past one another Have “flow.” In constant, random motion. Organization of Particles Packed in a crystal arrangement Not organized Compressible?NoNo-particles in contact w/one another Yes. Much empty space btwn particles Definite Volume? Yes No-Take on size of container Definite Shape? YesNo-take on shape of container No-Take on shape of container

Solids Movement of Particles in a Solid Particles packed in a regular repeating pattern-”crystal” –see p –Crystal structureCrystal structure Some elements have more than 1 crystal arrangement-”allotropes”- : carbon

Solids (cont.) Allotropes of Carbon Diamond Graphite Comparing Diamond & Graphite

Another Allotrope of Carbon: Buckminsterfullerine: C 60

Solids, cont. Solids at room temp tend to be metal elements & ionic compounds. Have high melting points. –Ex: copper, salts Also some molecular compounds are solids. They have low melting points. –ex: living things, sugar,.

Non-Crystalline Solids Solids that don’t have a crystal structure Amorphous Solid-Lacks ordered internal structure: rubber, plastic, asphalt Glass- Transparent inorganic substances cooled w/o crystallizing –Arrangement of particles midway btwn that of a crystalline solid & a liquid –Breakage of glasses & crystalline solids differs

Gases & Kinetic Theory 1. Gas particles are molecules or atoms but a gas is mostly empty space. 2. Gas particles move in constant random motion.motion 3. Particles continue in a straight line until acted on by a force. 4. All collisions are perfectly elastic (no energy is lost or gained.)

Gas Pressure Gas pressure is the result of collisions of gas particles on an object Gas Pressure

Vacuum  A lack of gas particles (no particles = no gas pressure)

Atmospheric pressure results from the collision of air molecules with objects Measured with a barometer

Barometer Height of Hg in tube depends on pressure exerted by particles of air colliding with Hg in dish Affected by weather & altitude

Atmospheric Pressure Air density decreases with increased altitude. Why? Less particles higher up, therefore less pressure.

As Altitude increases - air pressure decreases On top of mountains - the air is thin (few particles)

Units for Measuring Atmospheric Pressure SI unit of measurement is the Pa (Pascal) Normal atmospheric pressure ~100,000 Pa 1atm = 760 mm Hg = kPa = 14.7 psi

Liquids Particles have greater attraction for one another than in gases, but less than in liquids. This is what gives liquids their properties…

Vapor Pressure When liquids are in closed containers, particles can escape from liquid to vapor form, but can’t escape the container. These particles collide w/walls of the container & cause VAPOR PRESSURE.

Vapor Pressure of Different Substances (“Volatility”) Compare isopropyl alcohol & water Which one evaporates more easily? So, which has more molecules in vapor form? More vapor molecules = more vapor pressure, so ______ is more volatile.

Vapor Pressure, cont. At constant vapor pressure, the rate of evaporation of liquid = the rate of condensation of vapor.

Vapor Pressure & Temperature∆ An increase in temp causes an increase in vapor pressure. This is b/c more particles have enough energy to escape the liquid. More frequent collisions of gas particles w/container = greater vapor pressure.

Boiling Point (2 Definitions) 1. temperature at which particles throughout liquid have enough energy to vaporize. 2. temperature at which vapor pressure = external pressure. SO BP CHANGES IF EXTERNAL PRESSURE CHANGES!

BP & Pressure Changes: Ex #1 At high altitudes, atmos- pheric pressure is less than 1atm, so it is easier for particles to escape a liquid. Therefore, BP is LOWER at HIGHER altitudes.

BP & Pressure Changes: Ex #2 In a pressure cooker, pressure is much higher than 1 atm. It is harder for particles to vaporize So BP is much higher (Food cooks faster.)

Plasma-the 4 th form of matter Most common form of matter in universe Least common form of matter on Earth Ionized gas very high temperature Electrons are stripped away Ex: fluorescent lights, lightning, stars

Kinetic Theory Particles of a substance are in constant random motion. The energy particles have b/c of their motion is called __________energy!

Temperature Measures Avg. Kinetic Energy of Particles Can use fahrenheit (F), celsius (C), or Kelvin (k) Kelvin Scale is best measure of kinetic energy Kelvin temperature is directly proportional to the energy of the particles. –Ex: if temperature of substance doubles, then the kinetic energy of the particles has doubled too!

Cont. Absolute zero is when particles stop moving. (This temp has never been reached.) It is equal to 0 K.

Celsius-Kelvin Conversions T K = (T C + 273) K (notice: no “°” symbol) T C = (T K -273) °C

Fahrenheit-Celsius Conversions T C = [(°F - 32) x 5/9] °C T F = (°C x 9/5 +32) °F

Temperature Units The units in Fahrenheit & Celsius scales are degrees. The units in Kelvin scale are kelvins.

Kinetic energy of a particle Depends on 2 things –Its mass –Its speed –See Figure (p 351 of text) –Compare the 1 st 2 containers H 2 at 300KO 300K Which has greater kinetic energy? Which is moving faster?

Phase Changes Evaporation &Condensation (Liquid  Gas)(Gas  Liquid ) Melting &Freezing (Solid  Liquid)(Liquid  Solid) Sublimation & SolidificationSublimation (Solid  Gas)(Gas  Solid)

Special Conditions for Sublimation In substances whose vapor pressure exceeds atmospheric pressure at (or near) room temp.

Phase Changes, cont. The Relationship Between Melting & Freezing Point Melting Point of Water is___ Freezing Point of Water is ___ Therefore, MP ___ FP  WRITE THIS ONLY The Relationship Between Boiling & Condensation Point Boiling point (Evaporation pt) of water is ___ Condensation point of water is ___ Therefore, BP ___ CP  WRITE THIS ONLY

Phase Diagrams The relationships between solid, liquid and vapor states are represented by a phase diagram

Phase Diagrams A line on a phase diagram represents the combinations of pressure & temp at which 2 phases exist in equilibrium The “triple point” is where all lines intersect. This is the conditions of pressure & temp at which all 3 phases can exist.

Phase Changes, cont. Temperature plays an important role! Things that affect the rate of vaporization –Surface area –Temperature –humidity

Phase Changes, cont. Notice What happens to the temperature when 1.ice begins to melt and 2.water begins to boil Water: Solid-Liquid-Gas

Heat of Vaporization You notice that the temperature ________ for a period of time when the boiling point is reached. The energy that is being added is being used to break bonds, not speed up particles (no increase in kinetic energy!) Therefore no increase in temperature until all bonds are broken. The amount of energy necessary to break the bonds is called “Heat of Vaporization” Each substance has a different H.O.V.

HOV Examples Water: Ethyl alcohol:

Change in Energy w/o Change in Temperature? hanics/energy/heatAndTemperature/chang esOfPhase/changeOfState.htmlhttp://id.mind.net/~zona/mstm/physics/mec hanics/energy/heatAndTemperature/chang esOfPhase/changeOfState.html Animated motion of particles in ice & liquid waterAnimated motion of particles in ice & liquid water

Heat of Fusion When water freezes into ice, its temp also stays the same for a while. During this time, there is energy released while bonds are formed. Therefore, no energy is lost by the particles (no decrease in kinetic energy.) This amount of energy released is called Heat of Fusion.