Name and describe the 4 states of matter.

1. Name and describe the 4 states of matter. • Solids—have definite shape because the particles are held tightly to each other and so they cannot move out of position—they can only vibrate in place. Solids have definite volume because the particles are very close to each other and cannot be compressed any closer. • Liquids—have no definite shape because the particles have enough energy to move over and around each other, so liquids flow into the shape of their container. Liquids have definite volume because the particles are very close to each other and cannot be compressed any closer. • Gases—have no definite shape because the particles have enough energy to move in all directions, so gases take the shape of their container and will completely fill it. Gases have no definite volume because the particles are far apart from each other, and can therefore be compressed. • Plasmas—have the same properties as gases (no definite shape or volume). However plasmas have even more energy than gases, so that the electrons in the atoms have been stripped away from the nuclei.

2. Describe the difference between crystalline solids and amorphous solids. Give examples of each. Crystalline solids have particles that are arranged in regular, repeating patterns. Examples: salt, metals, gems. Amorphous solids have randomly arranged particles. Examples: glass, plastics, wax.

3. Use the Kinetic Theory of Matter to describe the properties of solids, liquids, and gases. SEE ANSWER TO QUESTION #1 ABOVE

4. Use the KT of M to describe thermal expansion. Thermal expansion is the change in size of a material due to changes in temperature. As a material is heated, the particles gain energy and move faster. In solids, the particles are fixed in position but they vibrate more rapidly when heated. As particles collide with other adjacent particles, they are pushed apart from each other slightly. This results in an overall expansion of the material.

5. Name and describe the different changes of state using the KT of M. • Liquification—occurs when a solid changes to a liquid. When energy is added to a solid, the particles move faster until they break free from the other particles around them. When this process is complete, the solid has melted into a liquid. • Solidification—occurs when a liquid changes to a solid. When energy is removed from a liquid, the particles slow down and become “attached” to other particles around them as bonds are formed between particles. When this process is complete, the liquid has frozen into solid. • Vaporization—occurs when a liquid changes to a gas. When energy is added to a liquid, the particles move faster until they are able to break away from the surface of the liquid. When this process is complete, the liquid has vaporized into a gas. • Condensation—occurs when a gas changes to a liquid. When energy is removed from a gas, the particles slow down and collect together. When this process is complete, the gas has condensed into a liquid. • Sublimation—occurs when a solid changes directly into a gas. When energy is added to certain solids, the particles speed up and break free from the other particles around them. These particles entirely skip the liquid state and go straight from solid to gas.

6. Compare and contrast boiling and evaporation. Boiling and evaporation are similar in that both involve liquid changing to gas and both require the addition of energy. They are different in the following ways: Boiling only occurs at the substance’s boiling point and involves large pockets of gas forming below the liquid’s surface. These pockets of gas then rise to the surface where they are released into the atmosphere. Evaporation occurs below the substance’s boiling point and involves individual particles leaving the surface of the liquid one at a time.

7. Describe the various regions of a heating or cooling curve for water. Region A—water is in the solid state and its temperature is rising as heat is being added. Region B—the water is melting and its temperature is steady at 0˚C as heat is being added. Region C—the water is in the liquid state and its temperature is rising as heat is being added. Region D—the water is boiling and its temperature is steady at 100˚C as heat is being added. Region E—the water is in the gas state and its temperature is rising as heat is added.

8. What are the temperatures at which water boils/condenses and melts/freezes in both Fahrenheit and Celsius? Melt/Freeze: 0˚C (32˚F) Boil/Condense: 100˚C (212˚F)

9. How does a substance “know” if it should freeze or melt when it reaches its freezing/melting point? When a substance reaches its freezing/melting point, it will melt if it is still a solid and heat is being added to it. If it is a liquid and heat is being removed, it will freeze.