Phys sci ch 2 sec 1 & 2mod reading


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Phys sci ch 2 sec 1 & 2mod reading

  1. 1. Chapter 2: The Properties of Matter Section 1: What is Matter Everything Is Made of Matter • Matter is anything that has volume and mass • Everything is made of matter Matter Has Volume • All matter takes up space • Volume is how much space an object takes up • Two objects cannot take up the same space at the same time Volume of a Liquid o Liquids have volume too. We use a graduated cylinder to measure the volume of a liquid. o Liters and milliliters are the units (label) for volume of a liquid Volume of a Solid o To measure volume you need to multiply length x width x height o cm or m are the units (label) used for volume of 3 3 solids o 1 ml = 1 cm 3 Volume of a Gas o Gas also has volume
  2. 2. Matter Has Mass • All matter has mass • Mass is the amount of matter something is made of • The only time an object’s mass will change is if the amount of matter in the object changes. The Difference Between Mass and Weight • Weight is different from mass • Gravity is a force of attraction between objects based on their masses • Every object has a gravitational force. This keeps everything on Earth from floating into space. (The bigger the mass, the greater the gravitational force) • Weight measures how much gravitational force is being put on an object Measuring Mass and Weight Mass and Weight are Different MASS WEIGHT • Mass is the amount of matter • Weight is a measure of the in an object gravitational force on an object • Mass always stays the same • Weight changes. It depends on no matter where on Earth the where the object is on Earth object is
  3. 3. • Mass is measured with a • Weight is balance measured with a spring scale • Units= grams (g), kilograms • Unit = Newtons (N) (kg), milligrams (mg) Chapter 2: The Properties of Matter Section 2: Describing Matter Physical Properties • A physical property is something that you can observe or measure about matter without changing the identity of the matter • Some examples are: color, odor, taste, texture, size, volume, mass, if it is a liquid or a solid • For example, some physical properties of water are that it is a liquid, it is colorless, and it is odorless Physical Properties Identify Matter • Physical properties help you to figure out what type of matter an object is • Use the chart on the next page to learn about other
  4. 4. important physical properties: Physical Properties The Property What it Means Example Thermal When something can Metal is a good Conductivity transfer heat from conductor. That is one area to another why your spoon becomes hot if you put it in hot soup State Whether the Ice is water when it substance is a solid, is a solid liquid, or a gas Malleability When something can Aluminum is be pounded into a malleable- it can be thin sheet without pounded into a thin falling apart sheet to make tin foil Ductility When something can Copper can be used be made into a wire for wiring Solubility When a something Sugar and salt can can dissolve in both dissolve in another substance water Density The amount of Lead is used to make matter in a certain sinkers for fishing space lines because it is
  5. 5. more dense than water and will sink Spotlight on Density • You find density by dividing mass by volume. Density = mass/volume • The units used for density are g/cm3, g/mL Using Density to Identify Substances • Density is useful for identifying substance. • It is the reason why a golf ball feels heavier than a table- tennis ball even through they are the same size. A golf ball feels heavier because it is more dense (it has more mass in the same amount of space than a table-tennis ball) • The density of an object does not change • The density of one substance is usually different than the density of another substance (every substance has its own density) Liquid Layers and The Density Challenge • Look at the picture on page 46 of your textbook (Figure 12). The jar is filled with 4 different liquids with different densities. The green substance is the most dense because it all sinks to the bottom. The yellow substance is the least dense because it floats
  6. 6. to the top. It does not matter how much of each of these liquids you have, the green substance will always sink to the bottom and the yellow will always float to the top because of their densities. Chemical Properties • Chemical Properties describe a substance based on its ability to change into a new substance with different properties. (Example: wood burning and turning into ash and smoke) • Some common chemical properties are: o Flammability (the ability for an object to catch fire) o Reactivity with oxygen, acid, or water Observing Chemical Properties • Chemical properties aren’t as easy to observe as physical properties Some Chemical Properties of Car Maintenance • Most cars are made of steel. Steel is made from iron. A chemical property of iron is that it reacts with oxygen, so when iron and oxygen come into contact, the iron rusts. Physical Vs. Chemical Properties • Characteristic properties are the properties that are the
  7. 7. most useful in identifying a substance. (Physical and chemical properties) • Examples are density, reactivity with acids, and solubility (able to dissolve) • Characteristic properties of a substance do not change Physical Changes Don’t Form New Substances • A physical change is a change that affects physical properties of a substance. • For example- if you break a piece of chalk into two pieces, you change the physical properties of size and shape. But no matter how many times you break it, chalk is still chalk. Examples of Physical Changes • Melting and dissolving are both examples of physical changes. • Freezing water • Sanding a piece of wood • Cutting your hair • Bending a paper clip • Crushing an aluminum can Can Physical Change Be Undone? • Physical changes do not change the identity of substances. During physical changes, the substance does not turn into a new substance • Physical changes are easy to undo
  8. 8. Chemical Changes Form New Substances • A chemical change happens when substances are changed into new substances with different properties • Example- When you bake a cake, you combine eggs, flour, sugar, and butter. Each ingredient has its own set of properties. When you mix the ingredients and bake them, you get something completely different, a cake, with different properties than any of the ingredients. Clues to Chemical Change • Chemical changes usually cause substances to change color, fizz, foam, bubble, heat, or produce sound, light, or an odor. Can Chemical Changes Be Undone? • Since new substances are formed during a chemical change, it is not easy to be undone • Example- You cannot unbake a cake