2. Matter

3. Chapter Five 5.2 Solid Matter

4. 5.2 Mechanical properties “Strength” describes the ability of a solid object to maintain its shape even when force is applied.

5. 5.2 Mechanical properties When you apply a force to an object, the object may change its size, shape, or both.

6. 5.2 Mechanical properties Elasticity describes a solid’s ability to be stretched and then return to its original size. Brittleness is defined as the tendency of a solid to crack or break before stretching very much.

7. 5.2 Mechanical properties A ductile material can be bent a relatively large amount without breaking. Steel’s high ductility means steel can be formed into useful shapes by pounding, rolling, and bending.

8. 5.2 The arrangement of atoms and molecules in solids If the atoms are in an orderly, repeating pattern, the solid is crystalline. Examples of crystalline solids include salts, minerals, and metals.

9. 5.2 Amorphous solids Rubber, wax and glass are examples of amorphous solids. The word amorphous comes from the Greek for “without shape.” Unlike crystalline solids, amorphous solids do not have a repeating pattern of molecules or atoms. Plastics are useful and important amorphous solids.

10. 5.2 What is heat? Heat is thermal energy that is moving. Heat flows any time there is a difference in temperature. Because your hand has more thermal energy than the chocolate, thermal energy flows from your hand to the chocolate and the chocolate begins to melt.

11. 5.2 Heat transfer Heat conduction is the transfer of heat by the direct contact of particles of matter. Conduction occurs between two materials at different temperatures when they are touching each other. Where is the heat energy conducted to and from in this system?

12. 5.2 Heat transfer Thermal equilibrium occurs when two bodies have the same temperature. No heat flows in thermal equilibrium because the temperature is the same in the two materials.

13. 5.2 Thermal conductors and insulators Materials that conduct heat easily are called thermal conductors and those that conduct heat poorly are called thermal insulators. Is a down coat a conductor or an insulator?

15. 5.2 Convection Convection is the transfer of heat through the motion of matter such as air and water. In a container, warmer fluid rises to the top and cooler fluid sinks to the bottom. This is called natural convection.

16. 5.2 Convection Convection is mainly what distributes heat throughout a room.

17. 5.2 Thermal radiation Heat from the Sun is transferred to Earth by thermal radiation. The higher the temperature of an object, the more thermal radiation it emits. All the energy the Earth receives from the Sun comes from thermal radiation.

18. 5.2 Thermal radiation Thermal radiation is also absorbed by objects. The amount of thermal radiation absorbed depends on the surface of a material. Dark surfaces absorb most of the thermal radiation they receive. Silver or mirrored surfaces reflect thermal radiation.

19. Chemistry Connection He named the compound “Silly Putty” after the main ingredient, silicone. Scientists who study how matter have another term for Silly Putty: it’s a viscoelastic liquid. Silly Putty In 1943, James Wright, a researcher for General Electric, dropped some boric acid into silicone oil, creating a gooey compound.

20. Activity The exact recipe for Silly Putty is kept secret, but you can make your own viscoelastic liquid with ingredients you may have around the house. Make your own viscoelastic liquid