KINETIC THEORY OF MATTER All matter is made of small particles in constant motion The higher the temperature the faster the particle motion At the same temperature, more massive particles move slower than less massive particles
SOLIDS Traditional definition: definite volume definite shape Expands only slightly upon heating Kinetic theory definition: 3-D vibratory motion about a fixed point
THERMAL EXPANSION Almost all matter expands as it gets hotter, and contracts when it gets colder As a solid is heated-particles begin to move faster and begin vibrating against each other with more force causing the particles to spread apart in ALL directions The particles do NOT get larger, it is the size of the spaces between the particles that increas
LIQUIDS Traditional definition: definite volume, no definite shape. Flow and take on shape of its container. Tend to expand upon heating Kinetic theory definition: particles undergoing rolling motion seeking lowest possible position
Traditional definition: no definite shape no definite volume (takes on shape and volume of container) Compressible Kinetic theory definition: high speed, straight line random motion
FYI: measurements indicate that the average speed of oxygen molecules in air at 20°C is an amazing 1700 km/hr. At these high speeds, the odor molecules from a hot cheese pizza in Washington D.C. should reach Mexico City in about 106 minutes. Why do they not reach Mexico City?
VAPOR –VS- GAS Gas-limited to those substances that exist in the gaseous state at ordinary room temperature Vapor-describes the gaseous state of a substance that is generally a liquid or solid at room temperature