Name: ___________________________________ Mrs. Polishchuk, Physical Science Unit 1.2 Lecture Notes WHAT MAKES MATTER “TICK”? Kinetic Theory 1. Explanation of how particles in matter behave. 2. All matter is made of atoms 3. Atoms are in constant motion 4. Diffusion: The spreading of atoms throughout a substance until they are uniformly distributed a. Occurs from collisions between atoms b. Atoms need “personal space” 5. Causes the atoms to “fight for space” and spread as evenly as possible 6. Atoms collide with each other and the walls of the container 7. Even solids vibrate in place. 8. Temperature measures kinetic energy 9. Higher temperature = faster motion; lower temperature = slower motion 10. Absolute zero a. -273 C or 0 K b. Lowest kinetic energy possible, motion is so slow that no more energy could be removed 11. Why did the hot balloon expand in lab? a. Increase in kinetic energy faster collisions with other atoms larger recoil from collision faster and more energetic collision with walls of the balloon. 12. Why did the cold balloon shrink in lab? a. Decrease in kinetic energy slower collisions with other atoms smaller recoil from collision slower and less energetic collision with walls of the balloon. States of Matter http://mutuslab.cs.uwindsor.ca/schurko/animations/waterphases/status_water.htm http://mutuslab.cs.uwindsor.ca/schurko/animations/phasescontainers/phasescontainer.html Solids 1. Atoms are closely packed together into a geometric arrangement: crystal structure 2. Lowest state of kinetic energy 3. Ice – geometric arrangement of water molecules 4. Atoms vibrate in place 5. Fixed volume and shape, high attractive force between atoms 6. Sketch a salt (NaCl) crystal Liquids 1. Higher in kinetic energy than solids 2. Energy absorbed from the environment allows atoms to overcome attractive forces from the solid structure and wiggle out of it. a. Melting point / heat of fusion: the amount of kinetic energy needed for this to happen 3. The higher state of kinetic energy allows liquids to flow a. Slide past each other and not be snagged into a geometric pattern b. Hydrogen bonding: Like a static electricity attraction, still cling together a little, gives a definite volume 4. Draw and label a hydrogen bond 5. Fixed volume, unfixed shape, some attractive force between atoms Gases 1. Higher in kinetic energy than liquids 2. Energy absorbed from the environment allows atoms to overcome attractive forces in the liquid state that makes liquids flow a. Atoms do not cling together b. Completely separate, no contact or attraction 3. Vaporization: the process of atoms escaping the “clingy” hydrogen bond a. Evaporation: occurs at the surface of a liquid only b. Boiling: pockets of gas form all over and escape at the surface c. Boiling point / Heat of vaporization: the amount of kinetic energy required for this to happen 4. Unfixed volume and shape, no attractive force between atoms Plasma 1. Most common in the universe 2. Matter consisting of positively and negatively charged particles 3. Highest kinetic energy – the collisions split the atom into pieces 4. Still neutral – equal number of positive and negative 5. Stars. florescent lights, neon lights, auroras Heating Curves 1. Shows temperature change as kinetic energy is added 2. Diagonal lines: increase in energetic state 3. Flat lines: absorption of energy occurring to overcome attractive forces in that state of matter. Thermal Expansion and Contraction 1. Examples: Thermometers, cracks in the side walk, pot holes, opening tight jars, hot air balloons 2. How are these examples of thermal expansion? What is Expanding? How does it happen? Thermometers high kinetic energy causes a need for more space for collisions, only way to expand is up Cracks and potholes in pavement Water collects in small pores in the pavement. When low kinetic energy ice forms, hydrogen bonds at low KE take up more space than hydrogen bonds in higher KE Opening jars high KE from hot water transfers some energy to the jar lid. Atoms in the jar absorb and take up more space when moving; expanding out Hot air balloons flame heats air inside the balloon, gives more KE to air molecules, they move faster collide harder and spread. Less dense that cold air outside balloon so floats. 3. The size of a substance increases when the temperature is increased a. More energy in collisions causes more pressure and bigger volume b. Expansion 4. The size of a substance decreases when the temperature is decreased a. Less energy in collisions causes less pressure and less volume b. Contraction 5. Water: the exception a. Expands when low in kinetic energy b. Hydrogen bonding causes large empty spaces when forming solids 6. Amorphous Solids are important to industry a. A = without Morphous = form b. No set boiling or melting point i. Glass, plastic c. Do not form crystal structure d. Molecules form chains that can be stacked or molded by manipulating temperature changes i. Obsidian: forms only when lava cools very quickly e. Liquid crystals are used in LCD (liquid crystal display) i. Substances that do not lose their geometric pattern in the liquid state of matter Properties of Fluids: Liquid 1. Two fluids: Liquids and Gases a. They “flow”: molecules are able to pass by with some interaction, but not so much that they are locked in a bond b. We live at the bottom of an ocean of air! 2. Buoyancy – the ability of a fluid to give an upward force on an object in it 3. Weight – the force of gravity plus an object’s mass 4. Why can huge ships float? a. A greater force pushes up on the ship than opposes the downward force of weight 5. If the buoyant force = weight, the object floats 6. If the buoyant force is less than the weight, the object sinks 7. Archimedes: Greek philosopher discovered the buoyant force a. Displacement: The weight of water pushed aside by an object b. The buoyant force an object receives is equal to the displacement of water c. The more water displaced, the higher the buoyant force 8. Draw the buoyant force vs. displacement a. Skinny, heavy ships sink because they do not push aside enough water b. Heavy, fat boats float because they push aside an equal amount of water as their weight. 9. Why does a ship’s hull need to be filled with air? a. The air makes the ship’s density less than water so it floats 10. Water can be pushed aside because it has a definite volume 11. Pascal discovered that fluids can exert pressure a. Force exerted per unit area or the weight of all fluid around an object b. Fluids flow from high pressure to low pressure c. Fluids transfer pressure from one area to another (squeezing a toothpaste tube) 12. Hydraulic lifts work using Pascal’s principle a. Pressure on a small cylinder is transferred to a larger cylinder b. The force gets multiplied over the area Properties of Fluids: Gases 1. Bernoulli’s principle allows for flight 2. Fast-moving fluid creates low pressure a. A fluid has “less time” to exert a force on its surroundings 3. Slow-moving fluids are higher in pressure 4. Airplane wings are airfoils that manipulate the flow of air into areas of different pressure a. Low pressure on top, high pressure on bottom b. High pressure pushes low pressure: lift force 5. Pascal’s principle allows for flight also a. Transfer of pressure from one area to another b. Force multiplied over the area of the wing 6. Other examples: Shower curtain 7. Air pressure is measured by a barometer a. Weight of air pushes liquid up a tube b. Units: Atmospheres (atm), Torr, mmHg (millimeters of mercury) c. Air pressure at sea level is 1 atm, 760 torr, and 760 mmHg d. Draw and label the parts of a barometer Behavior of Gases: Gas Laws 1. Gases are usually confined to containers a. Force of gravity creates the “container” for atmosphere, tires, balloons, basketballs, tennis balls 2. Collection of forces from collisions between gas molecules and gas molecules with its container have a set of relationships Boyle’s Law http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/gasesv6.swf 1. Pressure and volume are inversely proportional – they change oppositely 2. If volume decreases, pressure increases 3. P1V1 = P2V2 – Solve using algebra 4. From Lab: a. Cartesian diver – sketch it! 5. Draw it! Three canisters increasingly compressing a set volume and amount of gas 6. A helium balloon has 2L of air in it at sea level (1atm). What would the volume of the helium balloon be when it reaches the stratosphere with an air pressure of 0.5 atm? 7. A child received a balloon with 2L of air in the mountains, but when she traveled to her sea side cottage, the balloon deflated and wouldn’t float. Why did this happen if the atmospheric pressure changed from 0.7 atm to 1 atm? Charles’ Law http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/gasesv6.swf 1. Temperature and volume are directly proportional; they change the same way 2. As temperature increases, volume increases 3. Molecular motion causes volume (draw it) 4. Temperature is the measure of kinetic energy 5. The more kinetic energy gas molecules have, the more it pushes against its container, therefore the larger the volume. 6. From Lab a. Sketch the three different balloon temperatures: 7. V1/T1 = V2 / T2 – plug in numbers and solve using cross multiplication 8. Why do tires need to have air added when it’s cold outside? 9. A sample of oxygen gas has a volume of 4.55L at 25 degrees C. Calculate the volume of the oxygen gas when the temperature is raised to 45 degrees C (4.86L) 10. A certain glass container is designed to hold no more 2L of any liquid or gas. If the bottle is sealed with 2L of air at room temperature (25 degrees C) and is microwaved to a temperature of 45 degrees C, will the bottle survive?