1. IQRA MODEL SCHOOL, TANDUR.

2. Liquids And Gases Liquids will take the shape of anything they are poured into One gas particle will fill any container it is in IQRA MODEL SCHOOL, TANDUR.

3. Pressure Pressure is a force applied to a fluid Pressure comes from the constant collisions of atoms IQRA MODEL SCHOOL, TANDUR.

4. Intermolecular Forces Intermolecular forces are forces between separate atoms and molecules that are attractive at a distance but repulsive at a close range Once molecules become close enough to touch intermolecular forces become repulsive IQRA MODEL SCHOOL, TANDUR.

5. Melting And Boiling The melting point is the temperature at which a substance changes from a solid to a liquid When enough thermal energy is added, intermolecular forces are completely overcome and a liquid becomes a gas The temperature at which a liquid becomes a gas is called the boiling point IQRA MODEL SCHOOL, TANDUR.

6. Melting And Boiling Points Of Common Substances Materials have a wide range of melting and boiling points Most materials have a higher density as a solid than a liquid As water freezes molecules of water separate slightly from each other IQRA MODEL SCHOOL, TANDUR.

7. Evaporation Evaporation occurs when molecules go from a liquid to a gas at temperatures below the boiling point Evaporation takes energy away from a liquid because the molecules that escape are the ones with the most energy IQRA MODEL SCHOOL, TANDUR.

8. Condensation Condensation occurs when molecules go from a gas to a liquid below the boiling point Condensation raises the temperature of a gas because atoms in the gas have more energy than atoms in a liquid Condensation removes water vapor IQRA MODEL SCHOOL, TANDUR.

9. Convection Convection is the transfer of heat through the motion of fluids such as air and water Convection occurs because fluids expand when they heat up IQRA MODEL SCHOOL, TANDUR.

10. The atmosphere of Earth Air feels “light” because its 1000 times less dense than water Air is the most important gas to living things on the Earth The atmosphere of Earth is a mixture of gases IQRA MODEL SCHOOL, TANDUR.

11. Weather Earth’s weather is created by gigantic convection currents in the atmosphere Warmer air is less dense than cold air and therefore the warm air near the ground rises IQRA MODEL SCHOOL, TANDUR.

12. How Rain Forms Over the oceans, the warm air may be nearly saturated with water vapor At a high altitude, the temperature of the atmosphere drops rapidly Excess water vapor condenses to create rain and other forms of precipitation IQRA MODEL SCHOOL, TANDUR.

13. The Molecular Structure of Solids In a solid, thermal energy is not enough to overcome intermolecular forces of attraction Because the molecules are bound to each other, all solids have some ability to hold their shape when forces are applied IQRA MODEL SCHOOL, TANDUR.

14. Strength The concept of “strength” describes the ability of a solid object to maintain its shape even when force is applied IQRA MODEL SCHOOL, TANDUR.

15. Elasticity If you pull on a rubber band, its shape changes, and if you let it go, the rubber band returns to its original shape. Rubber bands can stretch many times their original length before breaking, a property called elasticity Elasticity describes a solid’s ability to be stretched and then return to its original size IQRA MODEL SCHOOL, TANDUR.

16. Brittleness Brittleness is defined as the tendency of a solid to crack or break before stretching very much Heating causes molecules to move faster, temporarily breaking the force that hold them together IQRA MODEL SCHOOL, TANDUR.

17. Ductility A ductile metal can be bent a relatively large amount without breaking One of the most useful properties of metal is that they are ductile IQRA MODEL SCHOOL, TANDUR.

18. Crystalline solids Crystalline solids are solids that have an orderly, repeating pattern of molecules or atoms Most naturally occurring solids on earth are crystalline Metals like steel are also crystalline One of the most important crystalline elements is silicon IQRA MODEL SCHOOL, TANDUR.

19. Amorphous Solids Most plastics are examples of amorphous solids Amorphous solids do not have a repeating pattern of molecules or atoms Examples of amorphous solids include rubber, wax, and glass IQRA MODEL SCHOOL, TANDUR.

20. Heat conduction Heat conduction is the transfer of heat by the direct contact of particles of matter Conduction works through collisions and through the intermolecular forces between molecules Thermal equilibrium occurs when two bodies have the same temperature IQRA MODEL SCHOOL, TANDUR.