http://www.harcourtschool.com/ac tivity/states_of_matter/ Section 16.1 http://www.harcourtschool.com/ac tivity/states_of_matter/ 1

Physical Change 2 IDENTITY DOES NOT CHANGE!! a change in size, shape, or state of matter All phase changes are physical changes!! may or may not involve energy changes and color changes 2

Distillation Separating a mixture through evaporating a liquid and re- condensing its vapor. Vapors from the liquid with the lowest boiling point form first and are condensed and collected 4

5

Chemical Change change in identity- changes the COMPOUND or SUBSTANCE

Kinetic Theory Explains how particles in matter behave All matter is composed of small particles Particles are in constant random motion Particles collide with each other and the walls of their containers constantly Produces pressure 7

Kinetic energy Total energy of a material’s Particles causes the particles to vibrate KE - energy of motion Low KE in solids High KE in gases Higher temperatures- more vibration 8

Average KE = Temperature Of a substance or how fast the particles are moving Lower in Solids,  Higher in Liquids  Highest in Gases 9

-273 ˚C Particle Motion Only temp at which No particle motion Absolute zero 0 K (kelvin) -273 ˚C 10

11

Solids particles have strong attraction for each other, preventing motion – held in rigid structure Particles are closely arranged in a specific type of geometric arrangement Crystal structure definite shape and volume 12

Solids- particles are closely packed Geometric arrangement of particles in a solid- determines chemical & physical properties of a solid Solids- particles are closely packed 13

Melting Different solids melt in different ways: Amorphous -solid that softens and gradually turns into a liquid over a large temperature range – don’t form crystals Ex. Glass, rubber, cotton candy, plastic, Coal 14

15

Crystalline solids- have set geometric structure-melt at a set temperature Water, NaCl (table salt), Diamond, Graphite, Sugar 16

17

Liquids Indefinite shape Definite volume Take the shape of their container 18

Liquids Particles have more space between them allowing them to Flow and take the shape of their container. Particles of a liquid have more KE than particles of a solid 19

Buoyancy The ability of a fluid (liquid or a gas) to exert an upward force on an object immersed in it The 2 forces acting on any object in a fluid are Weight Force and Buoyant Force 20

Buoyant force is equal to the object’s weight When object FLOATS Buoyant force is equal to the object’s weight 21

Viscosity A Fluid’s resistance to flow 22

Viscosity is different for different fluids because structure of fluids differs If moving particles don’t pull others into motion, liquid has high viscosity (slow flowing) 23

If moving particles do pull others into motion, liquid has low viscosity (flow easily) 24

How does Temperature affect Viscosity? Viscosity is greater when the substance is Cold particles move slower and transfer energy slower Ex. Syrup that’s Cold vs. micro-waved syrup 25

Gas particles have enough energy that they have escaped the attractive forces that held them in liquid state 26

Gas Indefinite volume and indefinite shape Takes shape and volume of container 27

Particle Motion - Gas Particles of a gas- have enough KE to overcome the attractions between them completely Spread and fill the container completely 28

Diffusion-spreading of particles throughout a container until they are uniformly distributed 29

30

Plasma Gas-like state of matter consisting of positive and negative particles Most common state of matter in universe 31

Changes in State of matter Also called phase changes. All are physical changes!!!

From solid to liquid in solids, particles move slowly Heat is added- particles move faster When have enough KE (moving fast enough), they overcome the attractive forces between the particles and escape the solid 33

Liquid State A solid begins to liquefy at the Melting Point- temperature at which a solid begins to liquefy. As the particles gain enough energy to over come their ordered arrangement Liquid State 34

At what temperature does water freeze At what temperature does water freeze? At what temperature does water melt? The temperature at which a substance melts  Melting point, is the same as the temperature at which it freezes Melting pt. = Freezing pt.

Liquid to gas Some particles of a liquid move faster than others and escape the attractive forces of other particles- allows them to enter the gas phase Call this Evaporation Can occur below its BP 36

Boiling- the Temp. at which the Pressure of a vapor in the liquid is equal to the external Pressure acting on the surface of the liquid 37

38

Boiling pt and Pressure Lower external pressure like on a mountain means lower boiling point Higher external pressure like at sea level means higher boiling point 39

40

What is sublimation? When a substance skips the liquid state. Goes straight from a solid to a gas Ex. Dry Ice

THERMAL EXPANSION Increase in the size of a substance with the temperature increases. Size of substance will decrease when temp decreases Expansion and Contraction occur in most Solids, Liquids and Gases 42

For Example: Thermometers energy is added particles of the liquid move faster & farther apart forces fluid upward through the thermometer 44

higher temperature = expansion = lower density = rises Hot air balloons rise higher temperature = expansion = lower density = rises 45

Analyzing Heating Curves

Heating Curve D E C B A A- SOLID is being heated- energy is used to increase temperature It is still a solid, just getting hotter or colder. 47

D E C B A B- Phase Change- heat of fusion - melting point – energy is used to overcome attractions b/w particles 48

Heat of fusion- the amount of energy required to change a substance from the solid phase to the liquid phase at its melting point 49

Substance is still a liquid only getting hotter or colder C-liquid is heated up- heat energy is used to increase temperature of liquid Substance is still a liquid only getting hotter or colder 50

D E C B A D- Phase change (liq to gas- heat of vaporization- boiling point- energy is used to overcome attractions 51

Heat of vaporization- amount of energy required to overcome the pressure at the surface of the liquid  Liquid to a Gas Energy needed to boil Phase change from Liquid to Vapor 52

D E C B A E – vapor or gas is being heated- energy is used to increase temperature of Vapor 53

Water- Essential to Life on Earth!! Has “+” and “–” regions Decrease in temperature-particles get closer together “-” from one particle attracts to “+” of other molecule Most Dense at 4 °C 54

Water Empty spaces in ice are greater than those in water Ice is less dense than water Different from all other substances  Water expands from liquid to solid! 55

Why might this occur??

57