Chapter 3: States of Chapter 3: States of MatterMatter

•Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

•Section 3.3 Phase ChangesSection 3.3 Phase Changes

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Describing the States of Matter

• Key Concept: Materials can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite or variable

• Shape and volume are clues to how the particles within a material are arranged.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Kinetic Theory• Under ordinary conditions, why are objects

solid, liquid, and gas?• Kinetic energy-energy an object has due

to its motion (**The faster an object moves, the more kinetic energy it has.)

• Key Concept: The kinetic theory of matter says that all particles of matter are in constant motion.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases• Solids

• Def.-the state of matter in which materials have a definite shape and a definite volume

• Definite-the shape and the volume of the object won’t change (does not mean they can never change)

• **Almost all solids have some type of orderly arrangement of particles at the atomic level.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• SOLIDS Have definite (or fixed) shape and volume

The particles in a solid are held fairly rigidly in place.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Explaining the Behavior of Solids• Key Concept: Solids have a definite volume and

shape because particles in a solid vibrate around fixed locations.

• **Strong attractions among atoms restrict their motion and keep each atom in a fixed location relative to its neighbors.

• Atoms vibrate around their locations but do not exchange places with neighboring atoms.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Liquids

• Def.-the state of matter in which a material has a definite volume but not a definite shape

• The arrangement of atoms is more random.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• LIQUIDS Have a definite volume but no fixed shape.

The particles in a liquid are free to flow around each other

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Explaining the Behavior of Liquids• Liquid particles have kinetic energy.• Particles in a liquid are more closely packed

than gas particles• A liquid takes the shape of its container because

particles in a liquid can flow to new locations.• Particles’ attractions do affect their movement.

(moving through a crowd of people)

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Gases

• Def.-the state of matter in which a material has neither a definite shape nor a definite volume

• **A gas takes the shape and volume of its container.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• GASES Have neither definite or fixed shape or volume.

The particles in a gas are: widely disbursed,

interact weakly,

move independently at high speed,

and completely fill any container they occupy.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Explaining the Behavior of Gases: Motion in Gases

• Particles in a gas are never at rest.• Some particles move faster or slower than avg.

speed of gas particles• Particles can collide with container walls or each

other causing one atom to slow down (lose kinetic energy) or speed up (gain kinetic energy).

• The constant motion of particles in a gas allows a gas to fill a container of any shape or size.

Section 3.1 Solids, Liquids, and Section 3.1 Solids, Liquids, and GasesGases

• Other States of Matter

• Most matter is solid, liquid, or gas.

• 99% of all matter observed in the universe exists in a state not common to Earth

• Extremely high temps (sun, stars); matter exists as plasma– Gases whose particles are so hot they have

acquired an electrical charge.

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Characteristics of Phase Changes

• What happens when a substance changes from one state to another?

• Phase- when at least (2) states of the same substance are present, what each different state is called

• Ex. Iceberg (solid) in the ocean (liquid)

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Characteristics of Phase Changes

• Phase change-the reversible physical change that occurs when a substance changes from one state to another

• Key Concept: Melting, freezing, vaporization, condensation, sublimation, and deposition are six common phase changes.

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Temperature and Phase Changes

• Measuring the temp. of a substance as it is heated or cooled is one way to recognize a phase change.

• Key Concept: ********The temperature of a substance does not change during a phase change.

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Energy and Phase Changes• Key Concept: Energy is either absorbed

or released during a phase change.• Endothermic change -the system absorbs

energy from its surroundings• The amt. of energy absorbed depends on

the substance.• **Heat of fusion (melting)-the amount of

energy absorbed for water (ice) to melt

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Energy and Phase Changes

• Ex. 1g of ice absorbs 334 joules (J) of energy as it melts; 1g of water releases 334 J of energy as it freezes

• Exothermic change-the system releases energy to its surroundings (freezing)

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Melting and Freezing• Key Concept: The arrangement of molecules in

water becomes less orderly as water melts and more orderly as water freezes.

• Melting-some molecules of water gain enough energy to overcome the attractions and move from their fixed positions

• When all molecules have enough energy to move, melting is complete.

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Melting and Freezing• Freezing-the avg. kinetic energy of water

molecules decreases (they move more slowly)

• Some molecules move slow enough for the attraction b/t molecules to have an effect

• When all the molecules are drawn into an orderly arrangement, freezing is complete.

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Vaporization and Condensation• Vaporization-the phase change in which a

substance changes from liquid into a gas• Is an endothermic process• 1g of water gains 2261J of energy when

vaporized (amt. of energy called heat of vaporization)

• 2 Vaporization processes: evaporation and boiling

Section 3.3 Phases ChangesSection 3.3 Phases Changes

• Vaporization and Condensation• Key Concept: Evaporation takes place at the

surface of a liquid and occurs at temperatures below the boiling point.

• Evaporation-the process that changes a substance from a liquid to a gas at temps. below the substance’s boiling point.

• Molecules near the surface move fast enough to escape the liquid (water vapor/open container)

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Vaporization and Condensation• In a closed container- water vapor collects

above the liquid• Vapor pressure-pressure caused by the

collisions of the vapor with the container’s walls (vapor press. ↑ as temp ↑)

• Boiling-when vapor pressure=the atmospheric pressure (i.e.. The temp. that this occurs at is the boiling point.)

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Vaporization and Condensation• Boiling- temp. goes up; molecules speed up;

(100oC) molecules below the surface have enough kinetic energy to overcome the attraction of neighboring molecules

• Boiling point depends upon atmospheric pressure.

• High elevation=atmospheric pressure is lower; water can boil at temperatures lower than 100oC (takes food longer to cook)

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Vaporization and Condensation

• Condensation- the phase change in which a substance changes from a gas or vapor to a liquid

• Is an exothermic process

• Ex. Dew on grass

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Sublimation and Deposition

• Sublimation- phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first

• Is an endothermic process

• Ex. Dry ice; cold CO2 vapor causes water vapor in the air to condense and form clouds

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Sublimation and Deposition• Deposition- when a gas or vapor changes

directly into a solid without changing into a liquid first

• Is an exothermic process and the reverse of sublimation

• Ex. Frost on windows; water vapor in air makes contact w/ cold glass; it loses enough kinetic energy to change from gas to solid

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Endothermic Phase Changes (energy is absorbed; state of matter goes from more orderly to less orderly arrangement of particles)

• Melting

• Vaporization

• Sublimation

Section 3.3 Phase ChangesSection 3.3 Phase Changes

• Exothermic Phase Changes (energy is released; states of matter go from less orderly to more orderly arrangement of particles)

• Freezing

• Condensation

• Deposition

Phase ChangesPhase Changes

Figure 16