1. Chapter 1: Properties of matter
Lesson 3: What are solids, liquids, and gases

2. States of Matter
Objective: Students will observe and measure properties of states of matter and will identify phase changes. Most materials around you are solids, liquids, or gases. For example, cooking oil is a liquid. Butter is a solid when cold,, but can turn into a liquid when it gets hot. If the motion and temperature of particles in a material changes, the state of matter changes. Lets compare and contrast: Look at the picture. How are the solid butter and liquid oil Alike and different?

3. sTATES OF matter
A solid is a substance that has a definite shape and volume. The particles of a solid are close together, they do not easily slide past each other, and stay in the same place.
A liquid is a substance that has a definite volume but no definite shape. The particles move by gliding past each other. Liquids can take the place of the container they are in.
A gas is a substance without a definite volume or shape. Gas particles a far apart. If a gas is placed in an empty container, its particles will spread out evenly and fill the space as well as take the shape of the container.
Plasma is like a gas because it has no volume or shape of its own. It is also like a metal because it can conduct electricity. The sun is made of gas and plasma.

4. FREEZING AND MELTING
The temperature at which a material changes between solids and liquid states has two names. It is called the freezing point when a liquid turns into a solid. It is called the melting point when a solid turns into a liquid. Therefore, the freezing point and melting point are at the same temperature. In pure substances, melting and freezing occur at the same temperature.
Discussion: Drivers in cold climates often add alcohol- based liquid to their cars to clean their windshields during the winter to keep their windshield from icing over. How does the alcohol keep the water in the cleaning fluid from freezing on the windshield?

5. Evaporation and condensation
Evaporation takes place when particles leave a liquid and become a gas. Particles evaporate from a liquid when they are at the surface of the liquid and are moving with enough speed. This is how rain puddles and the water in wet clothes evaporate. The boiling point of a liquid is the temperature at which bubbles of gas form throughout the liquid.
Condensation occurs when a gas turns into a liquid. This process often occurs when gas particles touch a cold surface and the temperature of the gas drops. Clouds in the sky and dew on the ground form through condensation of water vapor.
Discussion- What is the difference between evaporation and condensation?
The dew on this spider’s web formed before sunrise. What might this tell you about the air temperature before sunrise?