1. In this presentation you will: explore the different states of matter
explore the terms melting and boiling point
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2. In this presentation, you will learn about the main states of matter and how substances can be changed from one state of matter to another.
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3. What is Matter?
Every known substance that we can see or touch is composed of matter.
Solid
Liquid
Gas
Matter can be anything that occupies space and has mass.
All matter possesses a certain amount of energy. However, energy is not mass, as it cannot be weighed and it does not occupy space.
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4. What is Matter?
According to its temperature, pressure and the nature of the substance from which it is made, matter can be found in one of three main states.
Solid
Liquid
These three states of matter are solids, liquids and gases.
Gas
Substances exist as solids, liquids and gases at different temperatures.
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5. Solids The first state of matter that we will look at are the solids.
Solids have a fixed shape and volume and resist changes in form until enough force is applied.
If you put a solid in a container, it will keep its original shape and volume.
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6. Solids
The matter (atoms or molecules) that make up a solid are packed closely together.
As all matter also has some energy, the atoms must move around to some extent.
As the matter is tightly packed, its movement is restricted to vibration.
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7. Solids Solids can form many different structures. Some of them are:
Crystals, such as diamonds, ice and salt
Fine powders
Giant molecules, such as those found in living things
When solids are heated, they become liquids. The temperature at which this occurs is known as the melting point.
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8. Question 1
What happens to a substance at the temperature known as the melting point?
A) It changes from a liquid to a gas
B) It changes from a solid to a liquid
C) It changes from a liquid to a solid
D) It changes from a solid to a gas

9. Liquids
Liquids are the next state of matter. In many ways they are a half-way stage between solids and gases.
Liquids are fluids, whose shape changes to fit the container it fills.
Although liquids do not have a fixed shape, they still have a fixed volume, regardless of temperature and pressure.
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10. Liquids
Particles in liquids have more energy than solids, so they are more free to move around. They can slide over one another, which allows the shape of a liquid to change.
Some liquid particles have enough energy to escape from the surface and evaporate.
If enough heat is applied, the liquid will turn into a gas. This process is known as boiling.
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11. Question 2
"The shape of a liquid can change to fit the container it fills." Is this statement true or false?
Answer True or False.

12. Gases
Gases have no fixed shape or form. They can expand to fill whatever space they can occupy.
In gases, the atoms or molecules that constitute the matter move independently. As they have lots of energy, their motion is totally random and disordered.
This means that although they are usually separated, collisions of gas particles may occur.
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13. Gases
The volume of a gas is affected by temperature and pressure. The higher the temperature and the lower the pressure, the greater the volume of the gas will be.
0°C
Gases, like liquids, have the ability to flow from one place to another. This means that a gas is also a fluid.
100°C
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14. Question 3 Which of the following statements applies to gases?
A) They have no fixed shape or form
B) Their atoms or molecules move independently
C) Their atoms or molecules have lots of energy
D) All of the above

15. Plasmas
Another state of matter can be observed when a gas is heated to a very high temperature or electrically charged. This high-energy state is known as a plasma.
Although plasmas rarely occur on Earth, it is thought that most of the matter in the universe is actually made up of plasma.
Plasmas are used in many new technologies on Earth.
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16. Question 4
Which of the following states of matter has the least energy?
A) Solid
B) Liquid
C) Gas
D) Plasma

17. Melting Point
The melting point of a substance is one of its most important properties.
This is the temperature at which a substance turns from solid into a liquid. As it is affected by pressure, it is normally measured at standard conditions (sea level).
The melting point of water is 0°C (32°F) at standard conditions. This means that water is a liquid at room temperature (20°C, 68°F).
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18. Boiling Point
The other important temperature in describing a substance’s state of matter is its boiling point.
The boiling point is the temperature at which a liquid becomes a gas.
The temperature at which water becomes a gas (steam) is 100°C (212°F). Boiling points of other liquids may be much higher or lower than this.
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19. Question 5
The boiling point of ethanol is 78°C. If a beaker of water and a beaker of ethanol were both heated at the same rate, what would happen?
A) The water would boil first, then the ethanol
B) The ethanol would boil first, then the water
C) Only the water would boil
D) Only the ethanol would boil

20. Summary After completing this presentation you should be able to:
describe the main states of matter
describe the changes in states of matter
explain the terms melting point and boiling point
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