States of Matter & Changes of State Chapter 2 States of Matter & Changes of State

States of Matter we will study three different "states," or forms, of 
matter in this unit: Solid Liquid Gas When you identify a substance as a solid, liquid or a gas, you are identifying one of its physical properties.

Solids Solid- a state of matter that has a definite shape and definite volume. This means that a solid will not freely change what it looks like. The pencils to the left are solids. If left alone, they will maintain this shape and size. Look around the classroom and identify several objects that meet this criteria. Do those objects have a definite shape and a definite volume?

The particles don't move past each other, but vibrate. Pull Solids The particles of a solid are strongly attracted to each other. Solids will keep their shape because of this strong attraction. The particles don't move past each other, but vibrate.

SOLIDS Particles are tightly compact Particles vibrate without the ability to move freely Definite shape and volume Solid Animation

How are particles in a solid like people sitting in a movie theater? Question….. How are particles in a solid like people sitting in a movie theater?

Lets do a concept check…. What did we learn so far?

Answer : D 34 What are the characteristics of a solid? A & C A [This object is a pull 
tab] Answer A & C A Definite shape B Definite color C Definite volume D Both A and C Answer : D

35 An object with a definite shape will also always have a definite volume. [This object is a pull 
tab] Answer False True False Answer : False

Liquids The particles of a liquid are attracted to each other, but move more 
freely than the particles of a solid. Because of this, they are also referred to as fluids. Unlike in a solid, the particles of 

a liquid are able to move past 

one another.

Liquids Because the particles move freely around, a liquid has no definite shape. A liquid- the state of matter that has a definite volume but NOT a definite shape. The particles that make up a liquid have more energy than the particles 
in a solid. This causes them to move around quicker and keeps them 

from maintaining a definite shape.

Liquid Particles are tightly compact, but able to move around close to each other No definite shape, but definite volume Liquid Animation

Question.. Let’s go back to the movie theater reference How are particles in a liquid similar to people in a movie theater lobby?

Why does water change its shape? Think….. Question* Why does water change its shape? Think…..

Liquids Further Explained This concept can be confusing so we will look at an example: First, a student fills this bottle with water. Then, the student then takes this bottle and pours all of the water into an empty pot. In both situations, you have the same amount of water. However, 
because the bottle and the pot have different shapes, the shape of the 

water is now different.

Lets do a concept check…. What did we learn so far?

Answer: D 38 What are characteristics of liquids? A & C A [This object is a pull 
tab] Answer A & C A No definite shape B Definite color C Definite volume Answer: D

Answer: True 39 Liquids always take the shape of their containers. [This object is a pull 
tab] Answer True True False Answer: True

Gases When a substance is in the form of a gas, its 
particles are moving very quickly - more 

quickly than a solid or a liquid. Gas particles 

have more energy than solids and liquids. Question** What do you think happens to volume because of this? It ___________________ As gas particles move, they will fill all of the space available to them, no 

matter how much space the gas took up before. Gas- state of matter that has no definite shape and no definite volume.

Gas Particles can easily spread out or move close together Particle move freely and with a lot of energy No definite shape or volume Gas Simulation

Question.. Yes, the movie theater reference How are particles in a gas similar to people outside a movie theater?

Lets do a concept check…. What did we learn so far?

Answer - False 42 A gas has a definite shape and a definite volume. [This object is a pull 
tab] Answer False True False Answer - False

Answer - False 43 A gas can not change volume easily. False True False [This object is a pull 
tab] Answer False True False Answer - False

Changes of State

Changing States of Matter Matter can freely change from one state (also known as "phase") to 

another. *One of the most common ways for a phase change to occur is by a change in temperature. Temperature – A measure of how hot or cold something is, specifically a measure of how fast the particles in an object are moving

and will be moving quicker. Energy Previously, we learned that the difference between solids, liquids and gases is the amount of energy in the particles, or atoms, that make up the object. Energy is tough to define, but in this case, we can say that it is the speed at which the atoms move throughout the object. For example, more energy means that the particles are moving more and will be moving quicker. What happens when you have more energy? At right, you can see an example of gas particles in motion.

The Energy of Matter Order the objects from least energy to most ( #1 – 3) – Below each photo Least energy Most energy 1 2 3

Raising the temperature of an object will cause its particles to Applying the Heat Raising the temperature of an object will cause its particles to move more and to speed up. On the other hand, lowering the temperature will cause the particles to move less and to slow down.

Change in Energy - Change in State Every change of state requires a change in energy. This change can 
only occur if energy is added or taken away. Sometimes this energy can come from a change in pressure, but in this 
unit, we will focus on a change in heat. Least heat Most heat 1 2 3 Solid Liquid Gas

The solid begins to change into a liquid. Solid Liquid Adding thermal energy to a solid increases the temperature of the 

object. ***Increasing temperature causes the particles to move faster. When 
this happens, the rigid structure of the solid starts to break apart. The solid begins to change into a liquid.

The change in state from solid to liquid is - melting. In most substances, melting 
happens at a specific temperature 
called the melting point. The melting point is different for all objects. The melting point for ice is 
32° Fahrenheit (0° Celsius). 
That is the temperature at 
which ice becomes water.

The liquid now begins to change into a solid. Liquid Solid If thermal energy is removed, the temperature of the object 

decreases. **Decreasing the temperature causes the particles to move slower. 
When this happens, the particles align in a rigid structure. The liquid now begins to change into a solid. Explain this diagram. Why does this happen?

Freezing The change of state from liquid to solid is - freezing. 
Freezing is the opposite of melting and, therefore, the 

freezing and melting points are the same. When you put liquid water in the 

freezer, the water loses energy to the cold air in the freezer. When the water temperature drops 

to 32° Fahrenheit (0° Celsius) the water will freeze. Question* What temperature represents freezing and melting point of water?

Lets do a concept check…. What did we learn so far?

44 Particles of a substance at a warmer temperature have more thermal energy than that same substance at a cooler temperature. [This object is a pull 
tab] Answer True True False Answer- True

Boiling Boiling occurs when liquid that is below the surface changes to a gas 
as a result of heating. For example, when water boils, its particles 
bubble and the gas rises. The temperature at which a substance boils is called its boiling point. Every element and molecule has a unique boiling point, therefore it can 
help scientists identify unknown substances. Water boils at 100o C (212o F).

45 What happens to the particles of a liquid as they lose energy? [This object is a pull 
tab] Answer B A The particles move at the same rate. B The particles move slower. C The particles move more rapidly. Answer - B

The change of state from a liquid to a gas is - evaporation. Liquid Gas The change of state from a liquid to a gas is - evaporation. Evaporation occurs when 
the particles in a liquid gain 
enough thermal energy to 
form a gas.

Water freezes at ______o C. 50 Water freezes at ______o C. [This object is a pull 
tab] Answer 0o C Answer – 0

Gas Liquid The opposite of evaporation is condensation – change of state from a gas to a liquid Condensation occurs when particles in a gas lose enough thermal 
energy to form a liquid.

Lets do a concept check…. What did we learn so far?

Water boils at ______o C. 51 Water boils at ______o C. [This object is a pull 
tab] Answer 100o C Answer – 100

Phase Change Review GAS LIQUID SOLID condensation Drag and drop the 
terms next to the 
correct arrow. evaporation freezing melting