States of Matter

• Matter exists in three in main states
• Molecule - group of atoms bonded together
• Atom - small building block or unit of matter
• The arrangement of MOLECULES and how they behave determine the state of substance
• The amount of movement of the molecules and the distance between the molecules within the substance determine its state
• Solid - molecules are tightly packed together and don't move about much within the substance
• Liquid - molecules are some distance apart and can move about and bump into one another within the substance
• Gas - molecules are far apart and can move about freely within the substance
• A SOLID has a fixed structure, a definite shape. Its shape and volume do not change. Its molecules are tightly packed closely together in a particular pattern and cannot move about freely. Molecules are able to vibrate back and forth in their places, but they cannot break the rigid structure

  
• A LIQUID is a substance that flows freely. It does not have a defined shape, but it does have a fixed volume. The energy movement of its molecules causes them to overcome the attractive forces between them. This allows the liquid to take shape of the container that holds it. Although particles do move freely, they are still relatively close to one another

  
• The speed at which molecules move in a liquid is called VISCOSITY
• Viscosity the resistance to flow, sometimes referred to as the FRICTION between the molecules of the fluid
• A GAS is composed of molecules that are spread far apart. It does not have a fixed shape or volume

  
• Gas molecules have relatively HIGH KINETIC ENERGY, which means that they move quickly and are able to overcome the attraction between them and separate
• Compressibility - measures the change in volume resulting from applied pressure
• the changes in temperature and pressure affecting matter are called PHASE CHANGES
• MELTING occurs when solid turns into liquid
• The MELTING POINT is the temperature at which the solid melts
• Heat increases the kinetic energy (movement) of the molecules inside the solid. The increased energy and movement breaks the attraction between the molecules and allows them to move away from one another
• FREEZING is what happens when liquid becomes solid.
• As the temperature decreases, the molecules inside the liquid have lower kinetic energy (movement)
• The point at which a liquid becomes a solid is called the FREEZING POINT
• VAPORIZATION occurs when liquid turns to vapor (gas).
• Vaporization or evaporation happens when molecules break the surface and are in contact with the air
• CONDENSATION the opposite of vaporization-it occurs when gas turns to liquid.
• SUBLIMATION is when a solid becomes gas, without ever becoming a liquid
• Sublimation is rare, because it requires specific conditions to occur, such as the right temperature and pressure.
• When a gas turns into solid it's called DEPOSITION
• Phase diagram - a way to show the changes in the state of a substance as it relates to temperature and pressure