- Slides: 16
Matter • Matter is ANYTHING that has mass and takes up space.
Matter Is All Around Us • Where is it in our classroom? • • • Lab Tables Chairs People Pencils Books Even the air.
All Matter Has Mass • How do we find out how much matter and object contains? • • • Measure the mass. What tool do we use? What unit? Grams (g)
Mass vs. Weight • The mass of an object is always the same no matter where it is located. • Weight is a measure of the amount of gravity exerted on an object. We weigh less on the moon than on earth because the moon experiences less gravity. Our mass is the same. •
All Matter Has Volume • • The amount of space the matter occupies What tools do we use? What Units? • Liters (L) OR • Cubic centimeters (cm 3 ) Remember 1 m. L = 1 cm 3
Chemistry • Chemistry is the study of the properties of matter and how matter changes
Physical Properties • A Physical Property is a characteristic of a substance that can be observed without changing it into another substance. • • Color, Shape, Oder, Texture, Volume, Mass, Density, Conductivity, State A Physical Change is a change that affects one or more physical properties of a substance. • • If I rip a piece of paper up it’s still paper just a different shape If I dye water green it’s still water just water with green dye in it.
How do I know if it’s a physical change? • When deciding whether a change is a physical change or not, ask yourself whether you have the same substance you started with. • If the substance is the same, then the changes it underwent were all physical changes.
Density • Do all things that are the same volume have the same mass? • Density is the amount of matter in a given space. • Which is more dense: a 1 m 3 box of feathers or a 1 m 3 box of pennies? • Pennies – they’re not heavier, they’re more dense
Calculating Density • • Density = Mass Volume M D X V The unit for density is g/cm 3 or g/ml
• Density is useful for identifying substances for two reasons: Density stays the same for any SIZE piece of something • The density of one substance is usually different from that of another substance. •
Fool’s Gold? • To make sure you hadn’t found more fool’s gold (iron pyrite), you could compare the density of your nugget to the know densities on the chart. • • • D= M/V D= 96. 6/5 D= 19. 32 g/cm 3 Mass= 96. 6 g Volume= 5 cm 3 Substance Density (g/cm 3) Iron Pyrite 5. 02 Gold 19. 32
Brian. Pop Review
Try it out! A glass marble has a volume of 5 cm 3 and a mass of 13 g. What is the density of glass? What do you know? Volume = 5 cm 3, mass = 13 g Write the formula: D = m/v Substitute into the formula: D = 13 g 5 cm 3 Calculate: D = 2. 6 g/cm 3 Check that your units agree: Unit is g/cm 3. Unit of density is g/cm 3. Units agree. Answer: D = 2. 6 g/cm 3
Practice Problems 1. A lead sinker has a mass of 227 g and a volume of 20 cm 3. What is the density of lead? 2. A glass of milk has a volume of 100 cm 3. If the milk has a mass of 103 g, what is the density of milk? Answers: 1. 11. 35 g/ cm 3 2. 1. 03 g/ cm 3