STATES OF MATTER What are different states of matter and how does matter change state?

4 TYPES OF MATTER Solid Liquid Gas Plasma

STATES OF MATTER Based upon particle arrangement Based upon energy of particles Based upon distance between particles

SOLIDS Very tightly packed Vibrating in FIXED position Definite shape and volume

LIQUIDS  Tightly packed  BUT far enough apart to slide over one another  Indefinite shape  Definite volume

GASES  Very far apart  Move freely.  Undefined shape  Undefined Volume

PLASMA  Ionized gas.  Very good conductor of electricity  Affected by magnetic fields.  Indefinite shape  Indefinite volume.

Liquid crystals - rod-shaped molecules that flow like liquid and bend light. LCD’s – liquid crystal displays used in watches, thermometers, calculators and laptop computers. Amorphous Materials – no form: Not all solids are crystalline. The particles in an amorphous solid are not arranged in a regular, repeating pattern - do not form crystals. OTHER FORMS OF MATTER

WHAT IS A PHASE CHANGE? A change from one state of matter to another. Physical changes because: Only affects physical appearance, not chemical make-up Reversible

MELTING Solid to a liquid Molecules speed up, move farther apart, and absorb heat energy What do you think the energy absorbed is being used for?

FREEZING Liquid to a solid Molecule slow down, move closer together and release heat energy. What do you think the energy is being released from?

VAPORIZATION (BOILING) Liquid to gas. It occurs at the boiling point of matter. Molecules speed up, move farther apart, and absorb heat energy.

EVAPORATION Liquid to a gas on the surface of a liquid (occurs at all temperatures). Molecules speed up, move farther apart, and absorb heat energy.

CONDENSATION Phase change from a gas to a liquid. Molecule slow down, move closer together and release heat energy.

SUBLIMATION Solid to a gas. Molecules speed up, move farther apart, and absorb heat energy.

DEPOSITION Gas to a solid. Molecules slow down, move closer together and release heat energy.

MELTING & BOILING POINTS Boiling Point: The temperature at which a liquid changes into a gas. Melting Point: The temperature at which a solid changes into a liquid. What is a Freezing point?

GRAPHING A PHASE CHANGE

SUMMARY

WHAT HAPPENS DURING A PHASE CHANGE? During: heat energy is either absorbed or released. Endo vs Exo Heat energy released: molecules slow down and move closer together. Heat energy absorbed molecules speed up and expand.

PHASE CHANGES When a substance changes states Requires the input or the removal of heat energy Freezing exothermic process = energy released Melting = endothermic = energy absorbed Enthalpy (H) = the heat energy at constant pressure. ∆H – “change” in enthalpy = change in heat released or absorbed

INTERMOLECULAR FORCES Electrostatic Interactions between particles that cause them to “stick” together. Attraction between positive charges and negative charges Strongest in solids Weakest in gases. During a phase change IMFs are either are being broken/weakened or strengthened/formed At room temperature how do you think IMFs affect the state matter is in? For example: at RT why do you think O2 is a gas vs. Ethanol is a liquid?

During a phase change Temp REMAINS THE SAME Only heat energy is added or removed during a phase change. Heat of Vaporization - amount of energy absorbed when phase changes from liquid to gas Heat of Fusion – the horizontal segment of graph – when a liquid substance becomes a solid. Joule (J) = SI unit of energy HOW DOES ENERGY CHANGE RELATE TO TEMPERATURE CHANGE? CAN ENERGY INPUT CHANGE WITHOUT CHANGING TEMPERATURE? What did you observe in your lab?

HELPFUL INFO Melting point and freezing point are the same thing. It just depends if the substance is getting hotter or colder. During a phase change temperature does not change, but the amount of heat does.

HOW DOES THIS RELATE TO THE BURNS? Why does steam get ‘hotter’ and what does ‘hotter’ mean? What happens when steam hits your skin? Think about phase change and the energy…