Chapter 6: States of Matter

KMS 8th grade ScienceChapter 6: States of MatterIntroduction to ChemistryChemistry

Matter - The study of the properties of matter and how matter changesAnything that has mass and takes up space (that space is volume)Lesson 1 Solids, Liquids and GasesWhat types of matter do you see in this picture?Air (gas) Bubbles (liquid) Water (liquid) metal sign (solid)

Most Common Phases of MatterSolid Liquid Gas

How can matter be described?

StateColorTextureOdorMeasurements (volume, mass, density)SolidsMatter that has definite shape and definite volume.Arrangement of Particles:

How do these particles move?

Illustration of particle arrangement.Very close togetherVibrate in placeLiquidMatter that has no definite shape but has a definite volume.

Arrangement of Particles:

How do these particles move?

Illustration of particle arrangement.Further apart than particles in a solid (greater potential energy)More freely. Particles take shape of container.GasMatter that has no definite shape or no definite volume.Arrangement of Particles:

How do these particles move?

Illustration of particle arrangement.Large distance between particles. Greatest amount of potential energy.Quickly and freely. Particle illustrations

When talking about liquids you should knowViscosity

The stronger the attraction between forcesExamples: High Viscosity vs. Low Viscosity

Surface tension A measurement of a liquids resistance to flow.the higher the viscosity

Uneven forces acting on the particles on the surface of a liquid

When talking about gas you should knowVapor

Evaporation

The gas state of a substance that is normally a solid or a liquid at room temperature.

Vaporization that occurs only at the surface of a liquid.Lesson 2: Changes in StateWhat change of state are you observing?As a snowman melts you observe a solid turning into a liquid.

Changing an objects stateYou can change an objects state of matter by adding or removingWhen you add thermal energy:

When you remove thermal energy the opposite occurs: Particles slow down (kinetic energy decreases) or move closer together (decrease potential energy) or both.thermal energyThe particles move faster (increased kinetic energy) or move farther apart (increased potential energy) or both.Solid to Liquid or Liquid to SolidMelting

Freezing To change matter from a solid to a liquid. Thermal energy must be added.To change matter from a liquid to a solid. Thermal energy must be removed.During the solid phaseTemperature stops increasing when it reaches which is the temperature at whichThe horizontal line indicates that

Once the phase change is complete

The reverse occurs when going from a liquid state to a solid state. temperature and thermal energy increase.melting pointsolid changes to liquid.temperature has stopped increasing but thermal energy continues to increase.thermal energy (PE) slows down and temperature (KE) begins to rise again.

Liquid to Gas or Gas to LiquidBoiling

CondensationVaporization that occurs throughout a liquid. Changes liquid to a gas.The change of state from a gas to a liquid. When vapor cools back to a liquid.What is the main difference between evaporation and boiling?During evaporation a substance vaporizes only at the surface.

During boiling a substance vaporizes at the surface but also within the liquid.

During the liquid phaseTemperature stops increasing when it reacheswhich is the temperature at whichThe horizontal line indicates that

Once the phase change is completetemperature and thermal energy increaseboiling pointliquid changes to gastemperature (KE) has stopped increasing but thermal energy (PE) continues to increase.thermal energy (PE) slows down and temperature (KE) begins to rise again. The reverse occurs when going from a gas to a liquid

Is it possible for a solid to become a gas without becoming a liquid first?YES! This is calledSublimation

Deposition

SublimationThe change of state from a solid to a gas without going through the liquid stateThe change of state of a gas to a solid without going through the liquid state.Phase Changes

Energy can never be created or destroyed for matter to change phases thermal energy is transferred.

Lesson 3: Behavior of Gases

Pressure and VolumePressure

VolumeThe amount of force applied per unit of area.The amount of space an object occupies.Pressure and VolumeAs volume pressure with the same number of particles.

Does the number of particles change from the first illustration to the last?

What is happening in the picture?decreasesincreasesNo, the number of particles remain the same.As the plunger moves down, pressure increases and volume decreases.

Boyles LawPressure of a gas increases if the volume decreases and pressure of a gas decreases if the volume increases when the temperature is constant.Robert Boyle

Have your ears ever popped in an airplane or in the car? Use Boyles Law to explain how this happens.On the ground (at sea level) air pressure inside your ear and the pressure of the air surrounding your ear are equal. When you increase altitude air pressure surrounding your ear decreases while the pressure in your ear stays the same causing increase in volume. This causes the pain you feel.British scientist who was the first to describe the properties of gases.

Charless LawThe volume of a gas increases with increasing temperature, if the pressure is constant.

Jacque Charles

What happens to a full balloon if you take it outside on a cold winter day? French scientist who described the relationship between temperature and volume of gas.When the balloon is in the cold air, the temperature of the gas inside the balloon decreases, causing the particles to slow down and come close together. Fewer particles hit the inside of the balloon causing it to look deflated.