Matter

Chapter Five: The States of Matter 5.1 Liquids and gases (fluids)

5.1 Liquids and Gases (Fluids) A fluid is a form of matter that flows when any force is applied, no matter how small. Fluids take the shape of their container. Liquids are one kind of fluid, gases are another.

5.1 Liquids and Gases A force applied to a fluid creates pressure. Pressure acts in all directions, not just the direction of the applied force.

5.1 Liquids and Gases Forces in fluids are more complicated than forces in solids because fluids can change shape. The units of pressure are force divided by area. Liquids and Gases

5.1 Liquids and Gases The pressure inside your tire is what holds your car up. Which units are normally seen on car tires?

5.1 Liquids and Gases On the microscopic level, pressure comes from collisions between atoms. Every surface can experience a force from the constant impact of trillions of atoms. This force is what we measure as pressure.

Intermolecular Forces The forces between separate atoms and molecules that are attractive at a distance and repulsive at close range What holds water together in a liquid. Strongest in solids, weakest in gases and intermediate in liquids. Opposite from the amounts of thermal energy in the states of matter.

5.1 Melting and boiling The melting point is the temperature at which a substance changes from a solid to a liquid.

5.1 Melting and boiling The temperature at which a liquid becomes a gas is called the boiling point.

The melting point and freezing points are the same for each substance!

5.1 Melting and boiling points of common substances Materials have a wide range of melting and boiling points.

5.1 Melting and boiling points of common substances Most materials have a higher density as a solid than as a liquid. Water is an exception. Ice wouldn’t float if ice were more dense than water! Ice helps fish and other aquatic organisms to survive over long, cold winters because the protective layer keeps the water below it warmer.

5.1 Evaporation and Condensation Evaporation is when a liquid changes to a gas below the boiling point. Oceans, lakes, rivers, even plants experience this. Condensation is when a gas changes into a liquid at a temperature below the boiling point. Dew and a wet glass holding a cold drink are good examples

5.1 The Water Cycle Water exists in all three states on only one planet in our solar system, the Earth. The temperature extremes are in that perfect range to allow this amazing cycle to continue on our planet, recycling the substance all life is based on.