1. UNIT: PHYSICAL SCIENCE Chapter 9: Properties and Changes of Matter

2. PHYSICAL PROPERTIES OF MATTER

3. WHAT IS MATTER? Matter- included solids, liquids, and gases. Examples: mountains, footballs, lakes, clouds, and air. Mass- amount of matter in an object. Measured in units of grams (g) or kilograms (kg). Weight- the amount of the pull of gravity between the object and Earth An object with a large mass normally has a large weight. A balance is used to measure mass.

4. DENSITY

5. WHAT ARE PHYSICAL PROPERTIES? Properties- things you can observe with your senses. Odor, hardness, color, shine, mass, density Physical Properties- can be observed without changing the identity of the substance. When you describe a rock, the rock is not changing into something else- it stays the same. Examples: density, the substance’s ability to conduct electricity, magnetism A substance’s state, whether it is a solid, liquid, or gas, is another important physical property.

6. WHAT IS A PHYSICAL CHANGE? When heat turns a solid into a liquid or a liquid into a gas, the identity of the substance is unchanged. Physical Change- a change in size, shape, or state without forming a new substance. Example- an ice cube melting to liquid water. Different substances are in different states at room temperature. These substances also change state at different temperatures. Melting Point- temperature at which a substance changes from a solid to a liquid. Boiling Point- the temperature at which a substance changes from a liquid to a gas. Freezing Point- the temperature at which a substance changes from a liquid to a solid. All of these temperatures vary from substance to substance.

7. WHAT ARE MIXTURES? Mixture- any combination of two or more substances keep their own properties. Examples: tossed salad, chocolate milk Even though the substances in a mixture keep their own properties, you may not always recognize these properties Example: Milk is a mixture. If you add vinegar to milk it will separate the substances making up the milk.

8. TYPES OF MIXTURES Suspension- a mixture made of parts that separate upon standing. Example: Oil and water Can sometimes be separated using a strainer Emulsion- a suspension of two liquids that usually do not mix together. Example: the few seconds after you shake up oil and water Colloids- contains undissolved particles or droplets that stay mixed in another substance. Examples: Fog is a liquid-in-gas colloid, Smoke is a solid-in-gas colloid Solution - a mixture of one substance dissolved in another so that the properties are the same throughout. Example: Kool Aid mixed in water. The Kool Aid particles are soluble- they can be dissolved in water. When it is poured into the water it is a solute- substances that can be dissolved. The water is the solvent- part of the solution that dissolves the solvent. Alloy- solutions of one or more metals and other solids. 14-carat gold- an alloy of gold, copper, and silver Sterling silver – an alloy of silver and copper. Pennies are made of an alloy of copper and zinc

9. WHY DO THINGS FLOAT? Pressure- the weight or force on a given area. When an object is submerged in a fluid, the fluid “pushes” in on the object. The push is greater at the bottom than on the top, so the fluid pushes the object toward the surface. This push is called buoyant force. The amount of buoyant force equals the weight of the water that is displaced. Example: water rising when you get in a bathtub Buoyant force varies on the weight and density of the object.