Chapter 4 States of Matter

Key Vocabulary Matter Solid Liquid Viscosity Gas Surface tension Thermal energy Temperature heat Melting Freezing Vaporization Condensation Pressure Buoyant force Archimedes’ Principle Density Pascal’s principle

Foldable Pyramid Fold Side 1 Solid Side 2 Liquid Side 3 Gas

What is matter? Anything that has mass and takes up space Give me some examples of matter

States of Matter 3 common states 1 rare state Solid, Liquid, Gas Plasma- found in stars, lightning, and neon lights Common in the universe, but uncommon on earth

Solids Matter with a definite shape and volume Particles are moving in vibration patterns that are not seen by the naked eye Amorphous Solids Have no definite crystal structure Examples: rubber, plastic, glass Crystalline Solids Particles arranged in repeated 3-D structures called crystals Examples: Sodium Chloride (cube), diamond (pyramidal) Other examples: Sugars, sand, snow

Connection Amorphous solids are like lemons in a bowl Crystalline solids are like eggs in a carton

What is a Liquid? Has a definite volume, but no definite shape Takes the shape of any container it is poured into Particles move freely and allow shape changes

Viscosity A liquid’s resistance to flow High viscosity means that the liquid is very thick and does not run well Example: molasses Low viscosity means that the liquid pours easily Example: water

Gases Matter that does not have a definite shape or volume Particles are farther apart than in any other common state Can be expanded or compressed Decreasing the volume (compressing) moves the molecules closer together

What is energy? The ability to do work or make a change We will focus on the ability to make a change now Ability to do work comes after the holidays The energy associated with motion is called kinetic energy The chance that an object might exert energy is potential energy

Thermal Energy The total potential and kinetic energy Depends on the amount of energy in a substance as well as how much of a substance is present

Temperature The average kinetic energy of a substance What is the difference between temperature and thermal energy?

Heat The movement of thermal energy from an object with more kinetic energy to an object with less kinetic energy When a substance gains heat, it gets warmer When a substance is cooled, it looses heat What happens to the particles when they are cooled?

Specific Heat The amount of energy required to raise the temperature of 1g of a substance by 1 degree Celsius

Surface Tension The uneven forces acting on the surface of a liquid Cause the liquid to act as though there is a thin film across the surface This unseen force allows bugs to float on the surface of a liquid Believe it or not, you can actually float a needle on water due to surface tension

Surface Tension Lab Question: Can you place more drops of water on the surface of a penny than what will simply fit on the face of the penny? Hypothesis: If…Then…Because 1 drop at a time place water onto the surface of a penny When the surface tension breaks, record the number of drops in the data section of your science journal Repeat 3 times for accuracy

State Changes Get out your pyramid foldable We are going to complete the sides of the pyramid in the next few minutes

Melting When an object absorbs thermal energy The increase in thermal energy causes the substance to change from solid to liquid Amorphous solids do not change like other solids They simply get softer and moldable See figure 10 on page 109

Freezing When a substance looses thermal energy The substance changes from liquid to solid The temperature at which a substance freezes is known as freezing point

Vaporization When a liquid gains thermal energy Changes from a liquid to a gas Example: Water boiling into vapor 2 types of vaporization Boiling- air bubbles form within the liquid and rise to the surface Evaporation- water at the surface vaporizes, occurs at temperatures below the boiling point

Vaporization Demo I will place one drop of rubbing alcohol on the back of your hand In your science journal, record your observations for the next 2 minutes What happened?

Condensation Decrease in thermal energy rearranges the pattern of a gas Causes the gas to turn into liquid

Sublimation Change from solid form to a gas state without ever becoming a liquid Example: At room temperature carbon dioxide is a gas Dry Ice is the solid form of carbon dioxide At room temperature, dry ice instantly turns into a gas

Pressure Equal to the force exerted on an object divided by the area over which the force is exerted Measured in SI Unit: Force is measured in Newtons (N) Area is measured in square meters (m2) Therefore pressure is N/m2 or a unit called the Pascal (Pa)

Atmospheric Pressure The air around you presses on your with a great force, you are just used to the pressure so you don’t feel it Atmospheric Pressure on earth is 101.3Pa at sea level This is equal to 101,000 N Air pressure enables you to drink from a straw Sucking on the straw eliminates the air in the straw The air pressure then pushes the liquid up the straw where there is no longer air pressure pushing downward

Using a Straw

Why don’t you feel the pressure? The atmosphere pushes with equal force on the outside of your body as the liquid in your body pushes outward As altitude increases, air pressure decreases When you rise in an airplane or go up a mountain your ears pop. Why?

Buoyant Force An upward force that presses against an object being pushed downward by air pressure and weight If the buoyant force is equal to the combined forces, the object will float Archimedes’ Principle- the buoyant force of an object is equal to the weight of the fluid displaced by the object

Density The density of an object is crucial as to whether it will float Density is mass divided by the volume An object that is less dense than the fluid will float An object that is more dense than the fluid will sink An object that is equally as dense as the fluid will neither sink nor float, but remain in the same position in the water

So how do things float? If density determines the buoyancy of an object, what two factors must be considered to make an object float? How do you need to modify these factors to make an object float?

Effects of Volume and Temperature As volume decreases, pressure increases As Temperature increases, pressure increases also Bernoulli’s Principle Demo- observe and record in your science journal What will happen when I place the ping-pong ball on the air current? What will happen if I tilt the air current? What will happen if I decrease the air pressure?

Chapter Experiment: Build a Boat Get into your science teams Question: How does the volume of water displaced by a ship relate to the mass of cargo a ship can carry? Can you create a ship that can float on water and carry cargo? Hypothesis: If…then…because Procedures: Write your own procedures for this lab

Build-A-Boat Conclusions A ship can only carry a certain amount of cargo safely It can carry less high-density cargo than high-density cargo