States of MatterChapter 2
Three States of Matter
Section 1
Identify the three states of matter in this scenario:You come inside from shoveling some snow. You’re
cold, so you make some hot chocolate. You take a sip from the nice, steamy cup, but it burns your lip. You add an ice cube so you can drink it sooner.
Identify the three states of matter in this scenario:You come inside from shoveling some snow. You’re
cold, so you make some hot chocolate. You take a sip from the nice, steamy cup, but it burns your lip. You add an ice cube so you can drink it sooner.
Solid:
Identify the three states of matter in this scenario:You come inside from shoveling some snow. You’re
cold, so you make some hot chocolate. You take a sip from the nice, steamy cup, but it burns your lip. You add an ice cube so you can drink it sooner.
Solid: ice cubeLiquid:
Identify the three states of matter in this scenario:You come inside from shoveling some snow. You’re
cold, so you make some hot chocolate. You take a sip from the nice, steamy cup, but it burns your lip. You add an ice cube so you can drink it sooner.
Solid: ice cubeLiquid: hot chocolateGas:
Identify the three states of matter in this scenario:You come inside from shoveling some snow. You’re
cold, so you make some hot chocolate. You take a sip from the nice, steamy cup, but it burns your lip. You add an ice cube so you can drink it sooner.
Solid: ice cubeLiquid: hot chocolateGas: steam
ParticlesAll matter is made of tiny particles called atoms
and molecules. How the particles move determines whether an
object is solid, liquid, or gasParticles are attracted to each other, but the
faster the move, the more they can overcome their attraction.
SolidsSolids have a definite shape and volume.Particles are very close together, and there is a
strong attraction between them.Each particle vibrates in place, but is locked in position by the particles around it.
Kinds of SolidsCrystalline solid – have an orderly, three-
dimensional arrangement of particlesRepeating patterns of rows.Examples – iron, diamond, ice
Kinds of SolidsAmorphous – particles with no special
arrangementNo patternExample – glass, rubber, wax
LiquidsLiquids – have a definite volume, but not a definite
shape.Liquids take the shape of their containers.The particles in a liquid move fast enough to overcome some of their attraction, so liquids can flow.
Properties of LiquidsSurface Tension
A force that acts on particles at the surface of a liquid.
A liquid with a high surface tension forms rounded drops. A liquid with a low surface tension forms flat drops.
Properties of LiquidsViscosity
A liquid’s resistance to flowA stronger attraction between particles = higher
viscosity = slower flow
Which has a higher viscosity: Italian dressing or ranch?
GasesGases have no definite shape or volume. Gas particles move very quickly and can break
away from one another.Gases are compressible. The amount of space
in between particles can change.
Behavior of GasesSection 2
TemperatureTemperature is the measure of how fast the
particles in an object are moving.The higher the temperature, the faster the
particles are moving.The faster the particles are moving, the more
energy they have.
TemperatureA gas with a higher temperature will expand
more.If you fill a balloon in cold weather, it will need
more gas to be full. If it suddenly gets warm, it may pop because the gases expand.
VolumeWe know that volume is how much space an
object takes up.Because gases particles can move and spread
out, their volume depends on their container.It is possible to make balloon animals because the gases in the balloon can be compressed. A water balloon would just explode!
PressurePressure is the amount of force on an area.In gases, the pressure is the number of times
the gas particles hit the inside of their container.Why is the pressure of a basketball greater than
a beach ball?
There are more particles of gas in a basketball than in a beach ball. Basketballs are usually filled with a pump, while beach balls are generally filled by blowing them up.
Gas BehaviorTemperature, pressure, and volume are linked.Changing one factor affects the other two.
Boyle’s LawBoyle’s Law – for a fixed amount of
gas at a constant temperature, the volume of a gas is inversely related to the pressure.
Boyle’s LawThis means that as the pressure
increases, the volume decreases by the same amount.
Charles’s LawCharles’s law – for a fixed amount of gas at a
constant pressure, the volume of the gas volume and temperature change in the same direction.
Charles’s LawThis means that as volume increases,
temperature increases.
Changes of StateSection 3
Changes of StateALL changes of state are physical changes.To change an state of matter, you must add or
remove energy.
Water is the only substance that can be found in all three states at normal surface temperature and pressure.
Endothermic vs Exothermic
Endothermic – energy is gained as the substance changes state
Exothermic – energy is removed as the substance changes state.
MeltingChange of state from solid
to liquidEnergy is added Adding energy to a solid
increases the temperature of the solid, making the particles move faster.
Melting PointWhen a solid melts, particles must break some
of the attraction that holds them together.The point where they break is the melting point. Melting point is a physical property – it could
help you identify a substance.
Common Melting Points
What is the melting point of water?
FreezingFreezing is the change of
state from a liquid to a solid.
Energy is removed.Removing energy makes
the particles begin to lock in place.
Freezing point is the time when the liquid turns into a solid
Freezing PointWhen you put an ice cube tray in the freezer,
does it freeze as soon as it touches the cold air? Why or why not?
Freezing PointDoes the water in the ice cube tray turn into ice
all at once? Why or why not?
EvaporationEvaporation is the change of state from liquid to
gas.
Sweat is mostly water. When you sweat, the water evaporates. You feel cooler because your body is transferring energy to the water.
EvaporationThink about it: In our country, when it is hot we
usually wear skimpy clothing – bathing suits, shorts, tank tops, etc. In other parts of the world with hot climates, people wear long, loose, light-colored clothing. In hot parts of the world, people also tend to eat spicy food. Brainstorm why this might be a more effective way to keep cool.
BoilingEvaporation occurs at the surface of a liquid,
while boiling changes a liquid to a gas all throughout the liquid.
Boiling creates bubbles. The pressure inside the bubbles is called vapor pressure.
Boiling occurs when the vapor pressure equals atmospheric pressure.
Boiling PointThe boiling point is the temperature (and
pressure) at which a liquid turns to gas.This requires an input of energy, in order to
break the bond of liquid particles.
What is the boiling point of water?
What is the boiling point of water?212°F or 100°C
Atmospheric PressureWater boils at 100°C only at sea level. Because
boiling depends on atmospheric pressure, at higher altitudes, the boiling point is lower.
Ex. In Denver (in the Rocky Mountains) water boils at 95°C
CondensationCondensation is the change of state from a gas
to a liquid.Condensation is the reverse of evaporation, so
the condensation point occurs at the same temperature as the boiling point.
Condensation releases energy.
SublimationSublimation is when a solid changes directly into
a gas.This requires a high energy input to break the
solid bonds.Not highly common. Carbon dioxide and arsenic
often sublimate – it is difficult to find them in liquid form.
Temperature and State Change
Temperature is related to the speed of the object’s particles.
Temperature does not change until state change is complete.