and the Kinetic Molecular Theory (KMT) 9/3/09 Phases of Matter and the Kinetic Molecular Theory (KMT) 9/3/09 1

Phases of Matter & the KMT What is Matter? • matter = anything that has mass and takes up space (has volume). • YES = water, charcoal, glass, people, etc. • NO = light, sound, electricity • chemistry = the study of matter and how it changes. The KMT and Phases • kinetic theory of matter = explains the properties of matter All matter is made of atoms and molecules that act like tiny particles. These tiny particles are always in motion. The higher the temperature, the faster the particles move. At the same temperature, more massive particles move slower than less massive particles. 2

Phases of Matter & the KMT—con’t. The KMT and Phases • kinetic theory of matter = explains the properties of matter All matter is made of atoms and molecules that act like tiny particles. These tiny particles are always in motion. The higher the temperature, the faster the particles move. At the same temperature, more massive particles move slower than less massive particles. • There are three main phases (states) of matter: (Note: Plasmas don’t behave normally in chemical reactions, so we will not spend too much time on them.) Phase Structure Distance btwn. Particles Movement Solid Liquid Gas Plasma rigid, fixed very small vibration shape of container small fluid movement shape of container large very fast, random high-temp. phase in which atoms lose their electrons (ex: fluorescent bulb) 3

Phases of Matter & the KMT—con’t. Solid Liquid Gas Microscopic Views of Each Phase 4

Phases of Matter & the KMT—con’t. Phase Changes • energy = the ability to change or move matter. Required to change the phases of matter from one to another. • there are six different phase changes: melting = change in phase from solid to liquid (ex: ice turning into water) evaporation = liquid to gas (ex: puddles disappearing as temps. heat up) sublimation = solid directly to gas (no liquid) (ex: ice cubes shrinking over time, dry ice) • the three phase changes listed above are endothermic because energy (in the form of heat) is absorbed into the substance during the change. 5

Phases of Matter & the KMT—con’t. • the other three phase changes: freezing = liquid to solid (ex: hot candle wax cooling and solidifying) condensation = gas to liquid (ex: a cold drink “sweating”) deposition = gas directly to solid (no liquid) (ex: frost forming on cold surface, like early-morning grass) • the three phase changes listed above are exothermic because energy (in the form of heat) is released from the substance during the change. • important to remember: just because energy is absorbed/released doesn’t mean the temperature of a substance changes during the phase change. In fact, it stays the same! (more on this later) 6

Graphic Organizer Instructions Choose 3 main colors: one color for the matter you will draw in the beakers another color for the exothermic phase change arrows and a last color for the endothermic phase change arrows Draw a picture representing the arrangement of particles of matter of a solid in one beaker (it doesn’t matter which one you start at). Write “Solid” on the label. Choose another beaker and draw a picture representing the arrangement of particles of matter of a liquid in that beaker (it doesn’t matter which one you pick here either). Write “Liquid” on the beaker’s label. Go to the remaining beaker and draw a picture representing the arrangement of particles of matter of a gas in that beaker. Write “Gas” on the beaker’s label. Label the arrows with the correct phase changes that take place between the two phases represented in each pair of beakers. Be careful—use the correct terms! Color all the exothermic phase change arrows the same color, including the key arrow under the title. Color all the endothermic phase change arrows the same color, including the key arrow under the title (must be different from the exothermic arrows). Write a description of each phase on the lines closest to the beaker you are describing. Be brief, but detailed. Write your name, date, and period on the bottom of the page in the area provided. Turn it in!