Physical and Chemical Changes

Physical and Chemical Changes

Physical and Chemical Properties Everything around us has physical and chemical properties.

Physical Properties • Characteristics you can observe without changing the substance into something new. • Use your senses to describe • state of matter • measurement

Use your senses… How does it look, smell, sound, feel, taste (don’t taste it unless the teacher says it’s ok)

What state of matter is it? (solid, liquid, or gas)

Measure it….mass, weight, volume, length, width, height, density, temperature, magnetic?

Physical Properties • List as many physical properties as you can

Chemical Properties • Will it burn, explode, react with other elements? • Characteristics that you can only observe by changing the substance into something new. • You can’t always tell chemical properties just by looking

Chemical Properties • List as many chemical properties as you can

Physical and Chemical Changes Matter around us can undergo changes. Physical Changes Chemical Changes

Physical Change • A change in which the form or appearance of matter changes but not its composition • Change of state • Change of shape • Dissolving

Physical Changeschanging state melting – solid to liquid condensation – gas to liquid freezing – liquid to solid sublimation – solid to gas vaporization – liquid to gas deposition – gas to solid

Changes in States

Physical Changeschange of shape Matter can change shape cutting tearing grinding crumpling bending

Physical Changesdissolving When you mix or dissolve one thing into another, it is a physical change

Chemical Change • A change in which the composition of matter changes and new substances are formed • It cannot be turned back into the original substance

Chemical Change • Signs that a chemical change may have taken place • Color change • Absorption or release of energy • Odor • Formation of gases or solids • Can’t be reversed

Chemical Changes Iron + oxygen and water = rust silver + oxygen and water = tarnish

Chemical Changes Burned wood Cooked food

Chemical Changes Leaves turning in fall Spoiled food

Chemical Changes Lightning bug Antacid tablet

Physical or Chemical orange Orange juice Orange cake Chemical Physical Copper jewelry Statue of Liberty copper Physical Chemical

Law of Conservation of Mass The total mass of matter before and after a physical or chemical change is the same. Matter cannot be created or destroyed The particles inside the matter rearrange to form new substances

Law of Conservation of Mass Even though it appears that part of the candle disappears, it is just turned into a gas. • proven by Antoine Lavoisier

Physical Change Chemical Change Directions: Take out all of the laminated cards. Find the “Physical Change” and “Chemical Change” cards. Using the posterboard, put the “physical change” card on the left side and the “chemical change” card on the right side. Now take out the remaining cards and lay them out in front of you. As a table, look at the picture and read the description on the back. Decide whether your group thinks each one is a physical change or a chemical change. Once everyone has agreed, place the card on the correct side of the poster. Record your answers in the table on youR worksheet by placing an “X” in the physical or chemical change box:

Physical and Chemical Changes