2.  States of Matter  Solid  Particles close together  May only vibrate  Liquid  Particles not as close together  Particles may move past each other, but attracted to each other  Gas  Particles far apart  Particles may move past each other, NOT really attracted to each other  States of Matter  Solid  Particles close together  May only vibrate  Liquid  Particles not as close together  Particles may move past each other, but attracted to each other  Gas  Particles far apart  Particles may move past each other, NOT really attracted to each other

3. Particles close together May only vibrate Particles close together May only vibrate

4. Liquid Particles not as close together Particles not as close together Particles may move past each other, but attracted to each otherParticles may move past each other, but attracted to each otherGas Particles far apart Particles far apart Particles may move past each other, NOT really attracted to each other Particles may move past each other, NOT really attracted to each otherLiquid Particles not as close together Particles not as close together Particles may move past each other, but attracted to each otherParticles may move past each other, but attracted to each otherGas Particles far apart Particles far apart Particles may move past each other, NOT really attracted to each other Particles may move past each other, NOT really attracted to each other

5. Liquid

6. Gas

8. Kinetic Molecular Theory  Particles of matter are ALWAYS in motion  Volume of individual particles is  zero.  Collisions of particles with container walls cause pressure exerted by gas.  Particles exert no forces on each other.  Average kinetic energy  Kelvin temperature of a gas.

9. Measuring Pressure The first device for measuring atmospheric pressure was developed by Evangelista Torricelli during the 17 th century. The device was called a “barometer” Baro = weight Meter = measure

10. An Early Barometer The normal pressure due to the atmosphere at sea level can support a column of mercury that is 760 mm high.

11. Pressure  Is caused by the collisions of molecules with the walls of a container  is equal to force/unit area  SI units = Newton/meter 2 = 1 Pascal (Pa)  1 atmosphere = 101,325 Pa  1 atmosphere = 1 atm = 760 mm Hg = 760 torr