Changing States of Matter

What makes different states of matter of the same substance different?

• Their name
• The physical arrangement of their molecules 

How do solid molecules become a liquid on the particle level?

• When enough energy is added to the particles, they break and move freely, the change is called melting.
• Heating a liquid makes its particles move more quickly. Some particles near the surface gain enough energy to break free and become a gas. This is called evaporation.

What is happening to the temperature when a substance is melting?

• A substance remains at its melting point temperature while the substance is melting (the temperature does not change until after the solid has melted completely).
• A substance immediately starts to get warmer and warmer until it reach room temperature.

How do liquid molecules become a gas on the particle level?

• Heating a liquid makes its particles move more quickly. Some particles near the surface gain enough energy to break free and become a gas. This is called evaporation.
• As a substance cools, the particles loose energy and change back to a liquid. Example: Condensing happens on the outside of a glass that contains ice. The water vapor in gas state near the surface of the glass looses its energy and condenses (changes back to a liquid) on the glass surface.

How does a gas turn back into a liquid?

• As a substance cools, the particles loose energy and change back to a liquid. Example: Condensing happens on the outside of a glass that contains ice. The water vapor in gas state near the surface of the glass looses its energy and condenses (changes back to a liquid) on the glass surface.
• Heating a liquid makes its particles move more quickly. Some particles near the surface gain enough energy to break free and become a gas. This is called evaporation.

What are the two important temperatures for each individual substance? 

• Melting point
• Boiling point
• A & B