Chapter 4: States of Matter

Section 1: Four States of Matter

Vocabulary

• States of matter• Solid• Liquid• Gas• Plasma

Vocabulary

• States of matter– Physical forms of matter

• Solid– State of matter in which the volume and

shape of a substance are fixed• Liquid– State of matter that has a definite volume but

not a definite shape

Vocabulary

• Gas– State of matter that does not have definite

volume or shape• Plasma– State of matter that starts as a gas and then

become ionized – Has an electric charge

Matter: Moving Particles

• All matter is made of particles• States of matter depends on the motion

of those particles• “particles” = atoms and molecule – Molecule is a group of atoms that function as

one unit

Matter: Moving Particles

• Matter is in constant motion– Regardless of the state of matter– Even solid particles are in motion

Solids

• Particles very close together• Strong attraction between the particles• Particles do move– But not fast enough to overcome the

attraction between them– Particles locked in place– Only vibrate

Liquids

• Particles move fast enough to overcome some of the attraction between

• Particles collide with and slide each other• Particles stay close together– That is why the volume is fixed, but not

shape

Gases

• Particles have little attraction between them– Move freely – Collide randomly

• Amount of open space between particles can change– that is why the volume of a gas changes

Plasma

• 99% of the universe is plasma• No fixed shape or volume• Can conduct electricity– Inside are charged particles• Atoms with a positive or negative electric charge

• Occurs naturally in lightning & fire• Artificial = fluorescent lights & plasma

balls

Section 2:

Vocabulary

• Changes of state• Melting• Evaporation• Boiling• Condensation• sublimation

Vocabulary

• Changes of State– Change of a substance from one physical

state to another• Melting– Solid changing to a liquid

• Evaporation– Liquid changing to a gas

Vocabulary

• Boiling– Change of a liquid to a vapor (or gas), throughout

all of the liquid• Condensation– Change from a gas to a liquid

• Sublimation– Direct change from a solid to a gas

Energy and Changes of State

• All changes of state are physical changes– The identity of the substance doesn’t

change– Ice = H2O– Water = H2O– Steam = H2O

Energy and Changes of State

• Particles move based upon state• Particles have different energy levels in

different states– Liquid state has more energy than solid– Gas state has more energy than liquid

Melting: Solid to Liquid

• As temperature increases, so does particle movement

• The temperature at which substance changes from solid to liquid is melting point

• Particles absorb energy to overcome some of their attraction to each other– Slide past each other

Freezing: Liquid to Solid

• For freezing to occur, the attraction between particles must overcome the motion

• Decrease in energy

Freezing point and Melting point are the same temperature

Evaporation

• Liquid to a gas• Happens at the surface• Boiling is similar: liquid to gas– Occurs throughout the substance

Evaporation

• Atmospheric pressure affects boiling– Higher elevation substance boils at lower

temperature• Less pressure, so particles can move easier

Condensation: Gas to Liquid

• Condensation and evaporation are opposite/reverse of each other

• Condensation point is temperature where a substance goes from gas to liquid– Condensation point and boiling point are the

same temperature

Condensation: Gas to Liquid

• Large numbers of particles clump together– Attraction overcomes their motion that has

been keeping them apart (gas state)– Energy has been removed• Temperature has decreased

Sublimation: Solid to Gas

• Direct change from solid to gas• Dry ice• Must have temperature change ( + )

Test Hint

• At what degrees Celsius does water boil at?– 100 ⁰C

• Since boiling occurs throughout the substance, does the volume of water affect its boiling temperature?– No !– It just takes longer to boil 10 L of water vs a 10

mL– Same is true for all substances

• Turn to page 114 –DRAW the picture at the bottom of the

page–Label as shown in textbook

• Turn to page 119–DRAW the picture at the bottom of the

page–Label as shown in textbook